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BSCS Biology: A Human Approach. Kendall/Hunt, 1997

Matter and Energy Transformations: Instructional Analysis

I: Providing a Sense of Purpose

Conveying unit purpose

Rating = Excellent
The material meets four indicators fully and mostly meets indicators 4 and 6.

Indicator 1: Met
Unit openers pose problems and questions that convey to students the purpose of the unit. For example, Unit Three: Energy, Matter, and Organization: Relationships in Living Systems opens with a picture of runners in a race (pp. 138–139s). The text raises several questions that relate the performance of the runners to matter and energy needs: “What exactly is energy, and where does it come from? How is energy related to the matter we take in each day as food? How do matter and energy help organisms like us perform?” (p. 139s).

The text then presents the unit purpose, which relates matter and energy to the runner’s performance and to other organisms:

In this unit you will explore matter, energy, and the relationship between them. You will investigate how matter and energy can explain levels of human performance that allow a runner to sprint to the finish line. Then you will see how cellular processes in the body extract energy from the food consumed by this runner and where the energy present in food originates. You also will see how matter and energy link all of the organisms in a community.

p. 139s

Chapter openers also present purposes to students. For example, Chapter 9: The Cycling of Matter and the Flow of Energy in Communities uses a representation as a basis for presentation of the chapter’s purpose. The analogy provided tells how a school community is like a community of living organisms. Students then read, “In this chapter you will use your experiences from a variety of activities and related essays to develop an understanding of how matter and energy are organized within communities” (p. 185s).

Indicator 2: Met
The problems, questions, or representations used to convey the unit and chapter purposes relate to observable phenomena rather than unfamiliar technical terms and hence are likely to be comprehensible to students. For example, the photograph used to introduce Unit Three: Energy, Matter, and Organization: Relationships in Living Systems shows competitors in a footrace, probably like many students have watched on television if not at a track (pp. 138–139s). In the opener for chapter 9, an analogy relates the school community to a community of living organisms. Also, definitions for “community” and “ecosystem” are provided in this chapter opener (p. 185s).

Indicator 3: Met
The problems, questions, and representations used to convey the unit and chapter purposes are likely to be interesting to students. The purpose for Chapter 7: Performance and Fitness, for example, with its focus on human physical performance, is very likely to interest high-school students (p. 141s). An example of a problem about a phenomenon that is probably unfamiliar to many students, but that will also probably interest them highly, is the problem posed at the beginning of Chapter 8: The Cellular Basis of Activity. On the opening page, students read, “In this chapter you will begin to investigate the important relationship between matter and energy by considering examples of where and how energy is stored and released” (p. 165s). Immediately, in the initial chapter activity, students are engaged in reading an account, A Matter of Explosions, which tells about a grain elevator explosion and asks questions like, “How can energy be stored in grain?” and “Why do you think you do not explode when you eat grain products?” (p. 166s).

Indicator 4: Mostly met
While students are not offered an opportunity to think about the purpose of the unit, they are given an opportunity to think about purposes of chapters. Each chapter begins with an Engage activity that follows immediately after the chapter opening page, where the purpose has been presented. BSCS Biology: A Human Approach uses a progression from a general problem in the chapter opener to an example of this problem in the Engage activity. The purpose of the Engage activity in the material’s instructional model is, in part, to “focus students’ thinking on the learning outcomes” (p. xiiit). One purpose of Chapter 7: Performance and Fitness, for example, is to help students “explore your understanding of the term fitness and why being fit should be an important priority for all of us” (p. 141s). The initial chapter activity, Thinking about Fitness, engages each student in considering what is his/her personal definition of fitness and what are the most important factors that affect the level of fitness (p. 142s). In some cases student thinking about the sample problem is related through questions to the general problem presented in the purpose. This can be seen in the grain elevator explosion scenario for chapter 8, where students think about how energy can be stored in grain (p. 166s) after learning that one purpose of the chapter is “...considering examples of where and how energy is stored and released” (p. 165s).

Indicator 5: Met
Chapters within units are consistent with the unit purposes identified. For example, in unit three all chapters deal with the relationships among matter and energy. Chapter 7 deals with this topic at the human organism level, chapter 8 at the molecular and cellular level, and chapter 9 at the ecosystem level.

Activities within chapters are consistent with the stated chapter purposes. For example, in Chapter 8: The Cellular Basis of Activity, after the initial activity considering the grain explosion (pp. 166–167s), the activity Energy in Matter conveys the idea that the amount of energy in a substance is determined by the way the atoms of that substance are organized (pp. 166–171s). The activity Keep on Running! demonstrates that energy is contained in food as students measure the calories in food samples and design a nutritional snack (pp. 171–175s). Using Light Energy to Build Matter acquaints students with the process of photosynthesis (pp. 176–180s), explaining how energy gets into food in the first place. In Building Living Systems students see how cells can break down and build up molecules as they study how “your body can take in materials from a cow and make it a part of you” (p. 181s). In the Evaluate activity for the chapter, Tracing Matter and Energy, students trace the path of an atom of carbon from its position in a molecule of carbon dioxide in the air to its position in a human muscle protein (pp. 182–183s).

Indicator 6: Mostly met
Units do not return to the stated purpose at the end of the unit but chapters do return to the stated purposes in the sense that final activities in the chapter are related to the problems and purposes posed at the beginning. For example, in Chapter 7: Performance and Fitness, the first student activity engages students in Thinking about Fitness; in the final chapter activity, Marathon, students apply what they have learned in the chapter to an analysis of the performance of runners in a race.

A connection between the chapter 8 purpose and the end of the chapter is present but somewhat less clearly established. The purpose of chapter 8 is “to investigate the important relationship between matter and energy by considering examples of where and how energy is stored and released” (p. 165s). This is immediately followed by the grain elevator explosion scenario (pp. 166–167s). The last activity of the chapter, which requires students to trace the path of a carbon atom from its place in a carbon dioxide molecule in the air to its place in a protein molecule in human muscle, does not refer directly to the grain elevator explosion. However, in discussing student responses to this activity, the Teacher’s Guide recommends questions that do pertain to the chapter purpose. For example:

Question: What is the ultimate source of energy for the necessary events?

Suggested Response: Excluding the trapping of energy by chemosynthetic bacteria, the ultimate source of energy is solar energy, which is used initially in photosynthesis.

p. 282t, question 1b

Question: Explain the transfer of energy during these events.

Suggested Response: Energy is converted from solar into chemical energy. Energy stored in some molecules, such as sugars, starch, or proteins, later will be released, and some newly available energy, such as that stored in ATP, can be used to power other reactions. Some energy is converted into heat.

p. 282t, question 1c

Conveying lesson/activity purpose

Rating = Satisfactory
The material meets indicators 1 and 5 and somewhat meets indicators 2 and 4. It does not meet indicator 3.

Indicator 1: Met
The material conveys to students the purposes of all lessons, activities, and readings in the chapters reviewed. For example, for the activity Releasing Energy, students read, “In this activity you will begin to examine the relationship between matter, such as food, and energy” (p. 166s). For the activity A Matter of Trash, students read, “This activity will engage you in thinking about various forms of matter that you may consider to be waste and about what happens to this matter after you throw it out” (p. 186s). The purpose of reading essays in the back of the book is conveyed to students in directions such as this one, which is provided to students as a step in the procedures for the activity Exploring the Cycling of Matter in Communities:

To generate a context for your observations and prepare you to design your own experiment that explores the transformation of matter, read the essays Matter in Nature Is Going Around in Cycles...What Next? (page E132) and Worms, Insects, Bacteria, and Fungi—Who Needs Them? (page E135).

p. 188s

Indicator 2: Somewhat met
In most cases, such as those discussed for indicator 1, the activity purpose is comprehensible. However, in some cases the purpose might be too vague to be comprehensible to students. An example of a purpose that might not be comprehensible is, “This activity provides the tools for you and your teammates to compete in the Mud City Marathon Snack Contest for a prize that your teacher will announce” (p. 171s) for the activity Keep on Running! Another possibly incomprehensible purpose is given for the activity Energy in Matter: “In this activity you will investigate some of the links among matter, energy, and organization and attempt to describe the close relationship among them” (p. 166s). The abstract term “organization” used in this statement of purpose may be especially difficult for students to understand.

Indicator 3: Not met
Opportunities are not provided for students to think about the purposes of activities.

Indicator 4: Somewhat met
At a few points throughout the chapters, this material includes statements or questions that convey how the activity relates to the chapter purpose or how the activity relates to other activities in the chapter. For example, following a scenario about grass clippings eventually generating heat, the text relates the activity Generating Some Heat to the chapter purpose:

From your experiences in this chapter, you might guess that microorganisms were beginning to break down the clippings....In this activity you will elaborate on your knowledge of the cycling of matter and the flow of energy in communities.

p. 194s

Similarly, the activity Spinning the Web of Life is connected with other activities in the chapter by the following statement:

You have already explored how matter cycles through various communities, and you are aware that energy is stored in matter....Let’s examine the larger picture of matter and energy, of which you are a part.

p. 191s

The quotation refers to such chapter activities as Exploring the Cycling of Matter in Communities, in which students observe a community of earthworms and a community of snails and Anacharis (pp. 187–190s).

Indicator 5: Met
The material consistently engages students in thinking about what they have learned so far and what they need to do next. For example, in introducing the activity What Is in the Food You Eat?, the text states:

...From the previous activity, What Determines Fitness?, you know that the source of the energy required for fitness is food....how do food scientists know what nutrients are present in particular types of food? In this activity you will have the opportunity to determine the presence or absence of five specific nutrients in a set of foods that your teacher will provide. Then you will combine these test results with the dietary analysis that you completed in What Determines Fitness? to discover what you really ate last week.

p. 146s

Another example is when, in the introduction to the activity Structures and Functions, the text states:

Recall from the previous activity, You Are What You Eat, that the food you eat is broken down by the digestive system....In this activity you will think about how matter from the building blocks produced by the digestion of food becomes organized into larger structures that have very specific functions. You also will relate the importance of the relationship between structure and function to human fitness and performance.

p. 153s

Justifying lesson/activity sequence

Rating = Fair
The material somewhat meets the first indicator but does not meet the second indicator.

Indicator 1: Somewhat met
The units and chapters are organized in a logical sequence. For example, in Unit Three: Energy, Matter, and Organization: Relationships in Living Systems, it is logical to start with consideration of matter and energy on the level of the human organism, the level with which students are most familiar, in chapter 7; then to proceed to the cellular and molecular level in chapter 8; and to the ecological level in chapter 9.

The logic for the organization of activities within chapters is less apparent. For example, chapter 8 first has students read the scenario about the grain elevator explosion. The next activity, Energy in Matter, gives students experiences with various kinds of chemical reactions. In this activity they also read essays about how matter and energy are related and that energy is converted and conserved. Then the Mud City Marathon Snack Contest is introduced. The connection between this activity and the chemistry activity (Energy in Matter) is circuitous:

The connections among food, the energy stored in matter, the release of potential energy from molecules, and the importance of exercise to human performance was so interesting to one of your classmates that she decided to investigate the career opportunities for nutritionists and dieticians. She began by subscribing to several health and nutrition magazines. In last month’s issue of Athlete’s World, she ran across an interesting ad: Fortune, Fame & Food....

p. 171s

In the ensuing activity students determine the number of calories in three foods, devise healthy snacks, and read about cellular respiration. The next activity introduces photosynthesis. The logic in this sequence is not apparent.

Indicator 2: Not met
The Teacher’s Guide tells how the chapters are arranged in units but no rationale for this sequence is given. For example, the order of chapters in unit two is described as follows:

The learners begin the unit by exploring the concepts of internal environments, external environments, compartments, and membranes. Next learners investigate different systems in the human body, from the level of the cell to the body as a whole, in order to learn ways the human body maintains an internal balance. Then in Chapter 5, the learners extend their opportunity to learn about internal balance in the human body by applying the concept to some of the basic activities of life. In Chapter 6, the students study what happens when internal balance is disrupted in various ways. They also consider how humans can influence, both positively and negatively, their own health as well as the health of others.

p. 117t

In the description of the chapter arrangement in unit three, the material hints at reasons for the sequence chosen:

Energy and matter are required by the great diversity of life forms on earth. Throughout Unit 3 students learn how energy is related to matter and how energy and matter help organisms perform. To begin the unit, we engage the learner’s interest in energy and matter, a sometimes abstract concept for students, by investigating how the use of matter and energy can help account for the various levels of human performance and fitness. In Chapter 8 the learners develop a greater depth of understanding by examining how cellular processes convert energy into matter, extract energy from matter (food), and support a variety of activities. In Chapter 9 the learners develop greater breadth by learning how matter and energy link all of the organisms in a community.

p. 205t

However, nowhere is the teacher explicitly told the reasons for the sequence chosen. Fitness may be the theme of chapter 7 in order to make concrete the “sometimes abstract” (p. 205t) concept of energy and matter, but the material does not share this reasoning with the teacher. Nor is the teacher told why the depth of understanding needs to precede greater breadth.

For each chapter, the sequence of activities is clearly presented in the Teacher’s Guide. However, while the material describes the sequence of activities in a chapter, no rationale for the sequence is provided, telling, for example, why a particular Elaborate activity precedes another.

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II: Taking Account of Student Ideas

Attending to prerequisite knowledge and skills

Rating = Poor
Indicators 1, 2, and 3 are not met and indicators 4 and 5 are partially met.

Indicator 1: Not met
The material does not alert the teacher to specific prerequisite ideas or skills.

Indicator 2: Not met
The material does not alert teachers to the specific ideas for which the prerequisites are needed.

Indicator 3: Not met
The material does not alert students to prerequisite ideas or experiences that are being assumed.

Indicator 4: Partially met
Although they are not explicitly identified as prerequisites, four prerequisite ideas to the key ideas about the flow of matter and energy are addressed, in whole or in part, in this material. Some of the prerequisite ideas are elaborated upon with examples, and, in some cases, students have firsthand experiences related to the prerequisite ideas.

The prerequisite idea that “Food provides the molecules that serve as fuel and building materials for all organisms” appears in text introducing the activity What Is in the Food You Eat?:

From the previous activity, What Determines Fitness?, you know that the source of the energy required for fitness is food. Thus, the nutrients in food supply both the matter and the energy that your body requires for human performance.

p. 146s

Next, students identify the nutrients in several food samples in a laboratory experiment. They read the prerequisite idea again in an essay related to the experiment:

In its most basic sense, food is any substance that your body can use as a raw material to sustain its growth, repair it, or provide energy to drive its vital processes.

p. E91

Students encounter the prerequisite idea yet again in the introduction to a presentation of a videodisc, Introduction to Biosynthesis:

Food not only provides energy, but it also is the source of matter that animals use to produce new structures necessary for body maintenance and continued operation.

p. 152s

The idea that food is a source of energy is also presented in the activity Keep on Running! (pp. 171–175s), where students determine the calories in food samples. The Teacher’s Guide says, “This experience provides concrete information that enables the students to explain the idea that energy is contained in common food substances...” (p. 263t).

A second prerequisite idea addressed in the material is that “Arrangements of atoms have chemical energy.” This idea appears in the essay Energy Is Converted and Conserved: “The source of energy in molecules....The arrangement of atoms in molecules...affects the energy properties of those molecules” (p. E113s). However, the essay then goes into types of chemical bonding and the role of enzymes in biological reactions.

A third prerequisite idea is that “Different amounts of energy are [is] associated with different configurations of atoms and molecules. Some changes of configuration require an input of energy whereas others release energy.” Text presents the bolded part of the first sentence of this idea in the introduction to the activity Energy in Matter: “The precise amount of energy in any substance is determined by the particular organization of atoms, the building blocks of matter, in that substance” (p. 166s). In the activity itself students have firsthand experiences with the second part of the idea as they carry out exothermic and endothermic reactions (pp. 166–171s). Students are then asked to read the essay Matter and Energy Are Related, which also presents the third prerequisite idea:

...energy is stored within the structure of a molecule’s bonds and atoms....In an exothermic chemical reaction, heat is released when the atoms in molecules are reorganized, that is, when the chemical bonds between atoms are broken and new ones are formed. If a chemical reaction results in the production of heat, then the reaction is releasing energy....Processes that absorb, or take in, heat are called endothermic...such processes require an input of energy before they can occur.

pp. E108–E109s

A fourth prerequisite idea, that “[As in physical systems] Energy can only change from one form into another,” is also presented in this material. For example, in the essay Energy Is Converted and Conserved, text presents the idea and expands upon it by giving examples:

When electricity flows through the metal coils on a stove burner, making the coils red hot, it does more than ready the teapot for tea. It illustrates an essential property of energy: energy can be converted from one form into another. In this case electrical energy is converted into heat energy....power-generating dams harness the mechanical energy of water by passing the water over turbines, which rotate and convert the movement of the water into electrical energy....Exploding grain elevators are another example of the conversion of energy from a stored form (the molecules of grain dust) to heat (the energy of motion)....Energy transfer also takes place in your body, where food is supplied to the digestive system, nutrients and energy are removed and supplied to muscles and other tissues, and heat is produced.

pp. E110–E112s

The caption for Figure E8.6 makes the same point: “...When the energy needs of humans are high, our bodies convert storage molecules such as glycogen into a form of chemical energy that can be used to perform work...” (p. E112s).

The idea that energy cannot be created or destroyed, but can “only change from one form into another,” is presented in the same essay:

This phenomenon, called the conservation of energy, means that even though the amount of energy at one location can change, the total amount of energy in the universe remains the same.

p. E112s

With respect to matter transformation, only one prerequisite is treated. The prerequisite idea that “Carbon and hydrogen are common elements of living matter” is mentioned in the Teacher’s Guide: “Emphasize carbon, oxygen, hydrogen, nitrogen, phosphorus, and sulfur as the principal building blocks of all organic matter” (p. 261t).

However, two important prerequisite ideas are not addressed in this material. The first is the idea that, “Most of what goes on in the universe...involves some form of energy being transformed into another. Energy in the form of heat is almost always one of the products of an energy transformation.” The student text provides examples in the essay Energy is Converted and Conserved (pp. E110–E114s), but the generalization is not made. While the examples may be adequate to build ideas about energy transformation in individual organisms (such as the key idea that “[humans]...get energy to grow and function...[from] their food, releasing some of the energy as heat” [Idea c₂]) the generalization is needed for the idea that “At each link in a food web, some energy is stored in newly made structures but much is dissipated into the environment as heat. Continual input of energy from sunlight keeps the process going” (Idea d₂) and for students to appreciate that this need for continual input of energy is a property of systems in general.

Also missing is any treatment of the conservation of matter. Even though the material presents the carbon cycle, the discussion in Matter in Nature Is Going Around in Cycles...What Next? does not convey the important idea that the Earth consists of an essentially constant number of a few kinds of atoms that, like a kit of Legos or Tinkertoys, can combine and recombine (pp. E132–E135s).

Indicator 5: Partially met
In several cases links are made between prerequisite ideas and key ideas about the flow of matter and energy. The prerequisite idea that “Food provides the molecules that serve as fuel and building materials for all organisms” is linked with the ideas that “Other organisms break down the stored sugars or the body structures of the plants they eat (or animals they eat) into simpler substances, reassemble them into their own body structures, including some energy stores” (Idea c₁) and that “Other organisms break down the consumed body structures to sugars and get energy to grow and function by oxidizing their food, releasing some of the energy as heat” (Idea c₂). The link is made in the introduction to the activity You Are What You Eat:

Now you know what is in the food you eat, but once this food is inside you, how does it become useful to your body? What does your body do to this matter so that you can use the energy it contains for performance? How does your body prepare this matter so that you will have the building blocks necessary for growth and repair? In this activity you will look at digestion to understand the role it plays in preparing to release the energy stored in the molecules of food and in providing a source of building blocks for biosynthesis.

p. 151s

The prerequisite ideas “Arrangements of atoms have chemical energy” and “Different amounts of energy are associated with different configurations of atoms and molecules. Some changes of configuration require an input of energy whereas others release energy” are presented in the activity Energy in Matter (pp. 166–171s) and in the essays Matter and Energy Are Related (pp. E108–E110s) and Energy Is Converted and Conserved (pp. E110–E114s). A connection is made between these prerequisites and the idea that “Other organisms break down the consumed body structures to sugars and get energy to grow and function...releasing some of the energy as heat” (Idea c₂) in the second essay:

Stronger bonds result when the atoms that make up a molecule share their electrons. These bonds are called covalent bonds....The carbohydrate molecules glycogen (in muscles and liver) and starch (in plants) are complex molecules and rich sources of potential energy; each is a macromolecule with large numbers of covalent bonds....

Energy for cellular activity....The source of this energy is long-term storage molecules such as glycogen. These molecules are so large and inaccessible, however, that a cell cannot use the energy in storage molecules directly....cellular reactions convert some of the energy in large molecules into another form of chemical energy that can be used directly by cells....In these reactions the energy is used to help perform cellular work; the energy is not all wasted as heat.

pp. E113–E114s

The prerequisite idea that “...Energy can only change from one form into another” is presented in the essay Energy Is Converted and Conserved and then linked with the idea that “Plants....[release] some of the energy...as heat” (part of Idea b₂):

Exploding grain elevators are another example of the conversion of energy from a stored form (the molecules of grain dust) to heat (the energy of motion)....Grain dust contains a great deal of potential energy, but when this energy is released, it becomes active. Active energy is called kinetic energy.

p. E111s

A link is also established between the prerequisite idea and Idea c₂ when the essay continues:

Energy transfer also takes place in your body, where food is supplied to the digestive system, nutrients and energy are removed and supplied to muscles and other tissues, and heat is produced.

p. E112s

The caption for Figure E8.6 makes the same point: “...When the energy needs of humans are high, our bodies convert storage molecules such as glycogen into a form of chemical energy that can be used to perform work...” (p. E112s).

The point that energy can only change from one form into another is connected with Idea c₂ (and with part of Idea e) in the same essay:

Energy transfer also takes place in your body, where food is supplied to the digestive system, nutrients and energy are removed and supplied to muscles and other tissues, and heat is produced. Even through all of the intermediate steps necessary for this transfer, no energy is lost or created. This phenomenon, called the conservation of energy, means that even though the amount of energy at one location can change, the total amount of energy in the universe remains the same.

p. E112s

However, even though the text presents the prerequisite idea that “Carbon and hydrogen are common elements of living matter” on page 261t, it does not connect it to the idea that “Plants make sugar molecules from carbon dioxide (in the air) and water” (Idea a₁).

Alerting teachers to commonly held student ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The material presents none of the commonly held ideas that are relevant to the key ideas and have appeared in the scholarly publications, such as the following:

1. Students think that food is whatever nutrients organisms must take in if they are to grow and survive rather than those substances from which organisms derive the energy they need to grow and the material of which they are made (American Association for the Advancement of Science [AAAS], 1993, pp. 120, 342; Driver, Squires, Rushworth, & Wood-Robinson, 1994, p. 27).
2. Students think that food is a requirement for growth rather than a source of matter for growth (AAAS, 1993, p. 343; Driver et al., 1994, p. 60).
3. Students think that plants get their food from the environment (mainly from the soil) rather than manufacture it themselves (AAAS, 1993, p. 342; Driver et al., 1994, p. 30).
4. Students think that plants have multiple sources of food rather than that plants make food from water and carbon dioxide in the air, and that this is their only source of food (AAAS, 1993, p. 342; Driver et al., 1994, pp. 31, 60).
5. Students may think that organisms and materials in the environment are very different types of matter and are not transformable into each other (AAAS, 1993, p. 342).
6. Students may not believe that a plant’s mass may increase mainly due to the incorporation of matter from carbon dioxide (a gas) (Driver et al., 1994, pp. 32, 39).
7. Students may think that plants do not respire, or that they respire only in the dark (Driver et al., 1994, p. 34).
8. Students tend to regard food that is eaten and used as a source of energy as belonging to a food chain, while the food that is incorporated into the body material of eaters is often seen as something different and is not recognized as the material that is the food at the next level (Driver et al., 1994, p. 35).
9. Students may think that dead organisms “rot away”; they do not realize that the matter from the dead organisms is converted into yet other materials (AAAS, 1993, p. 343).
10. Middle school students seem to know that some kind of cyclical process takes place in ecosystems. Some students see only chains of events and pay little attention to the matter involved in processes such as plant growth or animals eating plants. They think of the processes in terms of creating and destroying matter rather than in terms of transforming matter from one substance to another. Other students recognize one form of recycling through soil minerals but fail to incorporate water, oxygen, and carbon dioxide into matter cycles. Students may see no connection between the oxygen/carbon dioxide cycle and other processes involving the production, consumption, and use of food (AAAS, 1993, p. 343; Driver et al., 1994, p. 65).
11. Students may think that matter and energy are converted back and forth in everyday (non-nuclear) phenomena (Schneps & Sadler, 1988).

Some sightings were found that may actually support misconceptions. In discussing the nature of food, the essay Food: Our Body’s Source of Energy and Structural Materials states:

In its most basic sense, food is any substance that your body can use as a raw material to sustain its growth, repair it, or provide energy to drive its vital processes....Water is an important nutrient that we often take for granted, but our bodies need enormous amounts of it in comparison to other nutrients.

p. E91s

This statement may reinforce the misconception that food is whatever nutrients organisms must take in if they are to grow and survive rather than those substances from which organisms derive the energy they need to grow and the material of which they are made (number one in the preceding list).

Another passage that may reinforce the same misconception appears in the essay Matter in Nature Is Going Around in Cycles...What Next?:

Not only does matter move through an ecosystem, but some of it makes a complete cycle within it. For example, when beavers die along the river, their bodies gradually decay, and the nutrients derived from their bodies eventually mix with the soil. Plants then acquire some of these nutrients from the soil, and in turn various animals (including beavers) feed on these plants. In this way nutrients that once were part of an animal’s body cycle through various types of matter and are taken up by another animal’s body.

p. E133s

The Teacher’s Guide discusses how in chapter 8, “[T]he learners develop a greater depth of understanding by examining how cellular processes convert energy into matter [emphasis added]...” (p. 205t). If the teacher conveys this idea to students, they might think that matter and energy are converted back and forth in everyday (non-nuclear) phenomena (number 11 in the preceding list), even though this idea is stated correctly in the essay on photosynthesis:

...photosynthesis, the series of reactions by which plants, algae, and some bacteria use the sun’s energy, in the form of light, to synthesize macromolecules from smaller, simpler molecules [emphasis added].

p. E123s

Indicator 2: Not met
Since the material does not present any commonly held ideas, it cannot be given credit for clarifying or explaining those ideas.

Assisting teachers in identifying their students’ ideas

Rating = Poor
The material provides only one question that meets indicators 1–4.

Indicator 1: Minimally met
Only three questions are provided that could be used to elicit students’ ideas about matter and energy transformations before instruction. Two questions are provided about the grain explosion scenario in the Engage activity in chapter 8: “How can energy be stored in grain?” and “Why do you think you do not explode when you eat grain products?” (p. 166s). Later, in the Engage/Explore activity at the beginning of Chapter 9: The Cycling of Matter and the Flow of Energy in Communities, students are asked to examine a sample of trash provided by the teacher. Students are then to “write a short description of what you think might happen to the matter and energy in this trash after it is thrown out” (p. 186s). However, these examples are not sufficient to probe for all the misconceptions students commonly have on this topic.

Indicator 2: Minimally met
The questions listed under indicator 1 are comprehensible but are insufficient to probe for all the misconceptions students commonly have about this topic.

Indicator 3: Minimally met
In the Overview to the Teacher’s Guide, the instruction model used in this material is described. The overall description of the “5 Es” model says that the model “allows students and teachers to experience common activities, to use and build on prior knowledge and experience, to construct meaning, and to continually assess their understanding of a concept” (p. xiiit). However, none of the descriptions of the “E” activities (Engage, Explore, Explain, Elaborate, and Evaluate) indicate that their purpose is to help the teacher identify students’ ideas about the key ideas related to matter and energy before instruction.

Only one task is identified as having the purpose of identifying students’ ideas before instruction. This task is given in the Engage/Explore activity at the beginning of Chapter 9: The Cycling of Matter and the Flow of Energy in Communities, when students are asked to examine a sample of trash provided by the teacher and are then to “write a short description of what you think might happen to the matter and energy in this trash after it is thrown out” (p. 186s). The Teacher’s Guide indicates that this is the purpose of the question:

Step 2

As the students record their ideas about the matter and energy in the trash, use this as an opportunity to assess the students’ prior knowledge of these concepts. Expect that some students will know that some of the matter may recycle, that is, be used by other organisms, some of it may be used again by humans, and some students may know that some energy is converted into heat.

p. 291t

Two questions about the grain explosion scenario (described under indicator 1) are not intended to help the teacher identify their own students’ ideas. Accompanying notes in the Teacher’s Guide indicate that the purpose of the questions is to stimulate student interest rather than to find out students’ ideas before instruction:

• How can energy be stored in grain?

  Students may have no answer for his question yet; its purpose is to pique their curiosity about stored or potential energy without formally applying that label. Draw students to the idea that energy is stored in grain, which is a source of food. They should know from Chapter 7 that food is the source of their energy.

• Why do you think you do not explode when you eat grain products?

  This question should help students speculate about how the energy in food is converted in the body and why there are no explosions. Students will learn about energy release in living systems throughout this chapter.

p. 256t

Indicator 4: Minimally met
The task “write a short description of what you think might happen to the matter and energy in this trash after it is thrown out” (p. 186s) requires students to make a prediction. However, this one task is not enough to probe for all the misconceptions students commonly have about the key ideas related to the flow of matter and energy.

Indicator 5: Not met
The material does not suggest how teachers may probe beneath students’ initial responses to questions designed to find out what students think before instruction.

Addressing commonly held ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The material does not explicitly address any commonly held student ideas.

Indicator 2: Not met
The material does not include any questions, tasks, or activities that are likely to help students progress from their initial ideas.

Indicator 3: Not met
The material does not offer suggestions to teachers about how to take into account their own students’ ideas.

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III: Engaging Students with Relevant Phenomena

Providing variety of phenomena

Rating = Poor
Since the rating scheme depends on how many phenomena meet both of the indicators, the report for this criterion is organized to reflect the overall rating rather than each indicator judgment.

The material provides almost no phenomena to support the key ideas about matter and energy transformations. Only two phenomena are provided and each addresses only part of a key idea. In no case is a whole key idea addressed, and no phenomena at all are provided for seven key ideas.

In the Explain section of Chapter 7: Performance and Fitness, students are engaged in a real-world experience with the bolded part of Idea c₁, “Other organisms [humans] break down the stored sugars or the body structures of the plants they eat (or animals they eat) into simpler substances, reassemble them into their own body structures, including some energy stores.” In this activity students investigate how starch can be broken down into sugars by action of the enzyme amylase (pp. 151–153s). Students can choose to investigate the effect of different variables (light, concentration, temperature, or pH) on the amylase/starch reaction. The link between the firsthand experience and the bolded portion of the key idea appears in text introducing the activity:

...Animals that eat plants can use starch in the same way. Starch is too large to be absorbed into the blood stream directly from the intestine, but many animals have enzymes that break down starch to small sugars. In humans the enzyme amylase, which is present in saliva, accomplishes the breakdown of starch.

p. 151s

In the Elaborate section of Chapter 9: The Cycling of Matter and the Flow of Energy in Communities, students build compost piles and measure the heat produced (pp. 193–196s). This experience relates to the bolded part of Idea c₂: “Other organisms break down the consumed body structures to sugars and get energy to grow and function by oxidizing their food, releas[e]ing some of the energy as heat.” Although students do not investigate the idea that the organisms in the compost pile break down matter and use the released energy to grow and function, they do observe that energy is released in the form of heat. A link is made with Idea c₂ in a question asked as part of the analysis of the experience:

Question: The heat that you noticed is a form of energy. In what form was this energy before it was released as heat? What happens to this energy after it is released as heat?

Suggested Response: Before the energy was released as heat, it was present in the molecular structures of the matter that the decomposers used as food. Heat energy that is generated by the decomposers goes into the environment and is no longer usable for energy in biological systems.

pp. 196s and 307t, question 3

The material includes one activity that could have been used to support a key idea but was not used to do so. In the activity, students measure the calories in various food samples (pp. 171–175s), but even though students are mimicking how organisms “burn” food to release energy (part of Idea c₂), they are not told how the technique they are using relates to the process of respiration that takes place in cells. This point is not made in either the student activity or the essays referenced in the activity (Controlling the Release of Energy from Matter [pp. E116–E117s] and Cellular Respiration: Converting Food Energy into Cell Energy [pp. E117–E120s]). Thus, no link is made between the experience and the part of the idea to which the experience relates.

Providing vivid experiences

Rating = Poor
Since the rating scheme depends on how many phenomena meet all of the indicators, the report for this criterion is organized to reflect the overall rating rather than each indicator judgment.

The material meets no indicators. Given that only two phenomena are provided, and that each of these addresses only part of a key idea, there is little to be judged for vividness.

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IV: Developing and Using Scientific Ideas

Introducing terms meaningfully

Rating = Poor
The material somewhat meets the first indicator but only minimally meets the second.

Indicator 1: Somewhat met
In its opening page describing BSCS Biology: A Human Approach to learners, the text says:

When we defined the word “better,” we decided that a better high school biology program would mean the following:

• more emphasis on the big concepts of biology and less emphasis on the vocabulary words of biology....

p. xvs

However, the material is inconsistent in its treatment of technical terms. In the front section of the book, which focuses on student activities, terms are usually presented in connection with relevant experiences. For example, in the Explain section of Chapter 7: Performance and Fitness, students investigate how enzymes break down food. A boxed section called Background Information presents and defines several technical terms needed for the investigation, such as “Amylase,” “Enzymes,” “Maltose,” and “Starch” (p. 152s). These terms are presented in a relevant context for students but are not the focus of what is to be learned from the activity. In a later lesson, the terms “heterotrophs,” “autotrophs,” and “photosynthesis” are introduced in connection with an experiment on photosynthesis (p. 176s). The word “biosynthesis” is defined only after text explains to students why cells must build complex molecules:

....Even after growth has stopped, your body must be able to make new cells to replace damaged or infected ones, a process that occurs wherever healing is necessary, such as at the site of a skin cut. Cells also must build small simple molecules, such as amino acids and simple sugars, into the more complex biological molecules, such as proteins and glycogen, that are important for your daily activities....

p. 180s

One word which seems non-technical, but which probably merits more definition in connection with experience than it is given, is the word “organization.” This word in its various forms is central to the understanding of ideas in chapters 8 and 9 (see pages 165s, 166s, 185s, and others).

The essays are inconsistent in linking technical terms to experiences. On the positive side, the essays in the back section of the book are introduced in connection with student activities presented in the front section. Therefore, many technical terms in the essays may be linked in student thinking to relevant experiences. For example, students are referred to the essay What Happens to the Food You Eat? in connection with their firsthand experience with the digestion of starch by amylase (pp. 151–153s). Thus, when the terms “enzymes” and “substrates” are presented and defined in the essay, students may relate these terms to their own laboratory experiences, even though the essay does not state such relationships (p. E97s).

However, sometimes the essays present technical terms without links to relevant experiences. This is particularly true for terms used in illustrations. For example, one diagram presents the terms “oxaloacetic acid” and “citric acid” without establishing a relevant context for students (p. E119s).

Indicator 2: Minimally met
The number of technical terms introduced in the student activities in the front section of the book is largely restricted to those needed to communicate intelligibly about the key ideas. This is not true of the essay section in the back of the book, where many more technical terms are presented than are needed for intelligible communication. Examples of such unneeded terms and information are the equation for ATP synthesis from ADP + P, “fermentation” (p. E121s); “electron transport system,” “Krebs cycle,” “NADH” (p. E117s); and “stroma” and “thylakoid” (p. E125s). Furthermore, the density of unfamiliar terms used in essays is often quite high, as illustrated below:

Enzymes are protein molecules that catalyze, or speed up, specific molecular reactions that otherwise would take place only very slowly. The molecules to which enzymes bind are called substrates; particular protein and carbohydrate molecules are examples of substrates. When an enzyme catalyzes a substrate reaction, the substrate is converted into a different molecule. For example, when you eat a steak, the stomach enzyme pepsin binds to steak proteins and, with other protein digestive enzymes in the small intestine, breaks down the proteins to their component amino acids, as illustrated in Figure E7.7b.

p. E97s

Representing ideas effectively

Rating = Fair
Since the rating scheme depends on how many representations meet all of the indicators, the report for this criterion is organized to reflect the overall rating rather than each indicator judgment.

Although the material has a number of seemingly simple diagrams, few are used to clarify key ideas about matter and energy transformations.

Ideas about matter and energy transformation in other organisms (Ideas c₁ and c₂) are potentially well represented. Two representations, if used together, could be helpful in clarifying the idea that “Other organisms break down [food]...into simpler substances” (part of Idea c₁). One shows the fate of consumed carbohydrates, proteins, and lipids (Figure E7.7b, p. E96s) and another represents the simpler substances of which they are made (Figure E7.8, p. E97s). It is too bad that similar diagrams are not used to represent the subsequent recombination of digested food into human body structures. Another representation could be used to clarify the relationship between the breakdown and storage parts of Ideas c₁ and c₂ in response to human energy demands. Figure E8.6 (p. E112s) shows that larger molecules are broken down into smaller molecules when energy needs are high, whereas storage is high when energy needs are low and accompanying text relates the figure to the idea of energy storage or use. And Figure E8.11 (p. E116s) represents the prerequisite idea that “Food provides the molecules that serve as fuel...for all organisms” although details in the diagram go well beyond the idea and could make the diagram incomprehensible to students.

And the idea that “At each link in a food web, some energy is...dissipated into the environment as heat” (part of Idea d₂) is somewhat clarified by a representation. Figure E9.14 (p. E141s) shows an energy pyramid and lists the amount of energy (in kcals) available at each trophic level. The representation is accurate, comprehensible, and is explicitly linked to the real world both by the use of pictures of organisms (grass, grasshopper, mouse, and hawk) and by accompanying text:

Each time that an organism uses energy, it loses part of the energy in the form of released heat. This means that only a portion of the solar energy that producers take up is stored in biomass that herbivores can eat....If we begin with 1 million kcals of solar energy entering the ecosystem, producers convert only a small fraction (0.8 percent) of this solar energy into plant biomass....The herbivores, such as the grasshoppers that feed on these plants, incorporate only 800 kcals into their biomass....the predators, such as the mice that feed on the herbivores, incorporate only 80 kcals into their biomass....Finally, the secondary predators, such as the hawk, that feed on the first level of predators, incorporate only 8 kcals into their biomass....

p. E141s

However, other key ideas are not adequately clarified. For example, Figure E8.20 (p. E124s) is not likely to clarify the key idea that “Plants transfer the energy from light into ‘energy-rich’ sugar molecules” (Idea a₂) because it does not represent the fact that the sugars are energy rich (so no transformation is shown). Similarly, the figure does not represent the matter transformation in terms of the recombination of elements (the level of sophistication intended by Idea a₁) because it does not show that sugars are made up of carbon atoms that have been rearranged from the CO₂ supplied. For the same reason Figure E9.7 (p. E134s) does not clarify the idea that “The chemical elements that make up the molecules of living things pass repeatedly through food webs and the environment, and are combined and recombined in different ways” (Idea d₁).

Furthermore, most of the representations related to the topic of matter and energy transformations are needlessly complex and present information well beyond the key ideas. Examples of such representations are the figures on pages E118s, E119s, E125s, E126s, and E128s.

Demonstrating use of knowledge

Rating = Poor
Demonstrating use of knowledge is not a feature of this material. The material meets no indicators.

Indicator 1: Not met
The material does not demonstrate the use of any of the key ideas. For example, it does not use any of the key ideas on the topic of matter and energy transformations to explain phenomena.

Indicator 2: Not met
No performances are provided.

Indicator 3: Not met
No performances are provided that could be identified as demonstrating the use of knowledge.

Indicator 4: Not met
No running commentary or criteria for judging a good explanation are presented.

Providing practice

Rating = Poor
Two kinds of questions and tasks were considered for this criterion: The Evaluate questions and the student tasks and questions requiring application of ideas presented in the text. Only a few tasks provided give students an opportunity to use key ideas on the topic matter and energy transformations and these tasks target only a few of the key ideas. Moreover, while the few tasks provided are interesting, they are so complex that students may have difficulty responding to them.

Indicator 1: Minimally met
The material does not provide a sufficient number and variety of questions/tasks for any of the key ideas. The material provides two tasks for one of the key ideas, one task each for three other key ideas, and no tasks for the rest. While a couple of additional tasks are provided that could give students a chance to use the key ideas, the suggested responses do not focus on them.

Two questions/tasks are provided for the idea that “Other organisms break down the stored sugars or the body structures of the plants they eat (or animals they eat) into simpler substances, reassemble them into their own body structures...” (part of Idea c₁):

Question: ...What happens when a foreign protein enters an animal?

Suggested Response: The idea should surface in the discussion that when foreign protein is ingested, the large macromolecules are first broken down to smaller subunits, then reassembled through biosynthesis into macromolecules that are characteristic of the consumer organism.

pp. 153s and 231t, Part B, question 2

Question: Construct a diagram or other visual aid to show a plausible set of events that could explain how a labeled carbon atom in a molecule of atmospheric carbon dioxide ends up in a human muscle protein....

Write at least one paragraph that explains the sequence of events that you have diagrammed. You should include both the flow of matter and the energy sources that make these events possible.

Suggested Response: (The Teacher’s Guide indicates that “Student answers need not be this complete” but that students should “understand that the muscle protein of humans is not deposited intact from the muscle protein of the cow” [p. 282t].)

• Labeled carbon dioxide from the air is taken up by a plant leaf through the stomates.
• Solar energy is trapped in chemical form through photosynthesis.
• The labeled carbon is fixed into sugars through reactions that use some of the energy trapped by photosynthesis.
• The plant uses these labeled sugars to synthesize labeled macromolecules, including labeled starch and labeled proteins.
• A cow eats the plant, which contains labeled macromolecules.
• In the cow, the labeled plant macromolecules are broken down to labeled amino acids and labeled sugars through digestive processes.
• The labeled sugars then are broken down further by the process of cellular respiration, which releases energy in the metabolically useful form of ATP.
• Energy from cellular respiration can be linked to the biosynthesis of protein, during which anabolic reactions incorporate labeled amino acids into protein. This labeled protein may be incorporated into muscle tissue in the cow.
• The cow is slaughtered and processed, then a human eats a hamburger that includes the labeled protein.
• Human digestion breaks down this labeled protein to its component amino acids, one of which contains the labeled carbon atom.
• Some amino acids may become involved in aerobic respiration, releasing energy. In biosynthetic reactions in the human, which require energy, the labeled amino acid becomes incorporated into muscle protein as the body rebuilds tissue after exercise. Thus the labeled carbon from carbon dioxide becomes incorporated into protein in a human muscle.

pp. 182–183s, questions 1 and 2; pp. 281–282t

The latter task could also give students an opportunity to practice using the idea that “Plants make sugar molecules from carbon dioxide (in the air) and water” (Idea a₁), though this idea does not appear to be required.

The material provides one question for the idea that “Other organisms...get energy to grow and function” (part of Idea c₂):

Question: How does the matter in the food become usable energy for the body? In particular, how does it help a marathon runner keep on running?

Suggested Response: As students describe cellular respiration, they should mention that energy release in cellular respiration is slow, stepwise, regulated, catalyzed by enzymes, and produces ATP and hydrogen carrier molecules rather than heat (exclusively).

pp. 175s and 269t, question 1

For the idea that “Plants get energy...[from] sugar molecules” (a small part of Idea b₂), the Teacher’s Guide and text provides the following discussion question, but the suggested response focuses more on gas exchange than on energy transformation:

Question: Do plants carry out cellular respiration? Explain your response.

Suggested Response: Plants, like other organisms, must have a way to release and use the energy stored in macromolecules such as carbohydrates. Thus they do carry out cellular respiration. The oxygen-requiring reactions that go on in mitochondria do use oxygen, but it is less than the amount produced during photosynthesis, so plants give off excess oxygen to the air.

pp. 180s and 276t, question 3

Similarly, for the idea that “At each link in a food web, some energy is stored in newly made structures but much is dissipated into the environment as heat” (part of Idea d₂), the Teacher’s Guide and text provides the following question, but the suggested response does not focus on the key idea:

Question: Suppose you found yourself snowed in for the winter in a remote mountain cabin with no way of contacting the outside world. You must survive for several months with only what is on hand to eat. Aside from a small supply of canned peaches, your only resources are two 100-lb sacks of wheat and a flock of eight hens. Discuss the relative merits of the following strategies:

1. Feed the grain to the hens and eat their eggs until the wheat is gone, and then eat the hens.
2. Kill the hens at once, freeze their carcasses in the snow, and live on a diet of wheat porridge and chicken.
3. Eat a mixture of wheat porridge, eggs, and one hen a week, feeding the hens well in order to keep the eggs coming until all of the hens are killed.

Suggested Response: Expect the students to apply the rule of eating low on the food chain and the logic of not trying to feed the chickens to keep them alive as well [as] feeding themselves. If they apply these ideas, the students would choose option (b).

pp. 198s and 310–311t, question 5

Other questions provided in the Teacher’s Guide require either less sophisticated ideas or ideas that go beyond the key ideas. For example, the question “Make a diagram or other visual representation that shows the energy source and carbon source for humans and three other species with at least one plant example and one animal example” (p. 275t) does not require knowledge of energy transformations but only energy sources, a less sophisticated idea. And the question “How does the internal structure of the chloroplast facilitate providing potential energy for making ATP?” (p. 276t) or “How does the trapping of light energy provide energy for carbon fixation?” (pp. 180s and 276t) requires knowledge of details of light and dark reactions of photosynthesis, which goes beyond key ideas about energy transformation.

Indicator 2: Somewhat met
The practice tasks described under indicator 1 are novel. However, since the number of tasks is insufficient for the set of key ideas, the material as a whole only partially meets this indicator.

Indicator 3: Not met
The material does not provide sequences of questions or tasks in which complexity is progressively increased. Rather, the questions and tasks provided are so complex, students may not be able to respond. For example, students are asked to trace a radioactive carbon atom through photosynthesis, digestion, synthesis, digestion, and synthesis (p. 182s); yet they are never asked to trace it through a single process. The question is a fine practice question, but, unless it is preceded by a series of simpler questions in varying contexts, students may not be prepared to answer it. And the question “What happens when a foreign protein enters an animal?” (p. 153s) expects students to respond with a generalized abstract answer, even though students have not yet been asked to respond to a question about a particular protein in a particular animal such as a human being.

Indicator 4: Not met
The material does not provide students first with opportunities for guided practice with feedback and then with practice in which the amount of support is gradually decreased.

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V: Promoting Students’ Thinking about Phenomena, Experiences, and Knowledge

Encouraging students to explain their ideas

Rating = Fair
The material somewhat meets three out of five indicators. Questions were examined in the Engage, Explore, and Explain activities in each chapter of Unit Three: Energy, Matter, and Organization: Relationships in Living Systems. While these sections contain a number of questions, only a few of them encourage students to explain their ideas about key ideas about matter and energy transformations. (Questions that are accompanied by a correct answer in the Teacher’s Guide were examined under the criterion Guiding Student Interpretation and Reasoning.) Questions often focus, instead, on aspects of experimental design.

Indicator 1: Somewhat met
The material provides a few opportunities for students to express their ideas about key ideas about matter and energy transformations, but it does not do so routinely. The following relevant questions are provided in the Engage, Explore, and Explain activities:

1. Read the story A Matter of Explosions (page 167), and think about the following questions:
   • What provided the energy in the grain explosion?
   • How can energy be stored in grain?
   • What started the explosion that released the energy?
   • Why do you think you do not explode when you eat grain products?
2. Contribute your thoughts to a class discussion.

p. 166s

1. Discuss how you would define matter and energy and how they are related. Based on these definitions, identify two or three examples of evidence that support the idea that matter and energy are related.
   
   Record your team’s definitions and examples in your journal. As you work, encourage your partner to generate ideas.

p. 168s

How does the matter in the food [you invented] become usable energy for the body? In particular, how does it help a marathon runner keep on running?

p. 175s

2. With your partner list three biological processes involving biosynthesis and/or breakdown that you think are necessary for maintaining the human body.
3. Choose one of the processes your team identified in Step 2, and write an explanation in your journal of how energy and matter are organized during this process. Consider the following questions as you write your explanation:
   • Why is this process necessary for survival?
   • What is a source of energy for this process?
   • What is a source of matter for this process?

p. 181s

3. With your teammates create a visual diagram, such as a concept map, that represents your current understanding of the cycling of matter through a community. Base your diagram on the two populations that you studied in this activity.

p. 190s

The intent of the preceding questions appears to be for students to express their own ideas. For example, for the concept map task just described, the Teacher’s Guide provides only general comments:

As the learners create their own concept map or visual diagram, remind them to include all information that is relevant to the cycling of matter in a community. You may want to collect the journals to assess the diagrams more closely.

p. 302t

Other questions appear to serve different purposes, such as guiding student interpretation of activities and readings or assessing student progress, rather than encouraging students to examine their own ideas. For example, when students are asked to participate in a class discussion on “What happens when a foreign protein enters an animal?” (p. 153s), the Teacher’s Guide gives only the correct answer (rather than indicating that the purpose of this discussion is student examination of ideas):

The idea should surface in the discussion that when foreign protein is ingested, the large macromolecules are first broken down to smaller subunits, then reassembled through biosynthesis into macromolecules that are characteristic of the consumer organism.

p. 231t

Similarly, the question “Do plants carry out cellular respiration? Explain your response” (pp. 180s and 276t) is accompanied by only the correct answer in the Teacher’s Guide:

Plants, like other organisms, must have a way to release and use the energy stored in macromolecules such as carbohydrates. Thus they do carry out cellular respiration. The oxygen-requiring reactions that go on in mitochondria do use oxygen, but it is less than the amount produced during photosynthesis, so plants give off excess oxygen to the air.

p. 276t

And the question “The heat that you noticed is a form of energy. In what form was this energy before it was released as heat? What happens to this energy after it is released as heat?” (pp. 196s and 307t, question 3) is accompanied by the following suggested response in the Teacher’s Guide:

Before the energy was released as heat, it was present in the molecular structures of the matter that the decomposers used as food. Heat energy that is generated by the decomposers goes into the environment and is no longer usable for energy in biological systems.

p. 307t

Indicator 2: Somewhat met
The questions described under indicator 1 include instances in which students explain their ideas (p. 181s), clarify their ideas with examples (p. 168s), and represent their ideas (p. 190s). However, the material does not provide a sufficient number of questions that ask students to clarify, justify, and represent their ideas on this topic.

Indicator 3: Somewhat met
Though the material does not provide an adequate opportunity for each student to express ideas about matter and energy transformations, it does include some questions to be answered individually (pp. 168s, 175s, 181s) or by small groups of students (p. 190s).

Indicator 4: Not met
Only one question gives students feedback by informing them about what is required to answer the question:

Use an explanation, diagram, model, or demonstration of your choice to construct a response to the question, How does your organism use matter and energy to maintain its organization?

You will know that you have addressed adequately the preceding question when your response

• indicates the organism’s source of energy and matter and how these are obtained from its surroundings,
• demonstrates how energy is stored and made available for its activities, and
• distinguishes the macromolecules that it is able to synthesize from the macromolecules that this organism must obtain from its external environment (through its diet or other means).

p. 181s

Indicator 5: Not met
The material suggests only one specific example of a possible student error and how the teacher should respond to it, and the task is included in the Evaluate section of the chapter (which is not intended to serve the purpose of encouraging students to explain their own ideas). The task asks students to trace the path of a carbon atom from atmospheric carbon dioxide to a protein molecule in a muscle (pp. 182–183s). The Teacher’s Guide suggests:

Students might discover [from the class discussion] that important steps, such as the conversion of plant macromolecules into cow macromolecules, were missing or incorrect in their diagram of events. Allow them time to correct these omissions or mistakes because the opportunity to reflect on previous thinking is an important part of the learning process.

p. 283t

Guiding student interpretation and reasoning

Rating = Poor
One indicator is somewhat met and another is minimally met.

Indicator 1: Somewhat met
After each student activity, the material includes a set of Analysis questions. Examples of questions that are relevant to the key ideas are:

Question: Participate in a class discussion about the question, What happens when a foreign protein enters an animal?

Suggested Response: The idea should surface in the discussion that when foreign protein is ingested, the large macromolecules are first broken down to smaller subunits, then reassembled through biosynthesis into macromolecules that are characteristic of the consumer organism.

pp. 153s and 231t, Part B, question 2

Question: Explain the basic matter and energy requirements needed for a muscle to contract.

Suggested Response: Muscles are composed of proteins and thus require matter in the form of proteins for their structure. As a source of energy, muscles require food molecules (indirectly), which are converted into usable energy in the form of ATP. This ATP powers contraction.

pp. 155s and 234t, question 1

Question: How does the matter in the food become usable energy for the body? In particular, how does it help a marathon runner keep on running?

Suggested Response: Clear explanation of cellular respiration, perhaps using diagrams.

pp. 175s and 269t, question 1;
p. 269t, scoring rubric chart, Content

Question: Do plants carry out cellular respiration? Explain your response.

Suggested Response: Plants, like other organisms, must have a way to release and use the energy stored in macromolecules such as carbohydrates. Thus they do carry out cellular respiration. The oxygen-requiring reactions that go on in mitochondria do use oxygen, but it is less than the amount produced during photosynthesis, so plants give off excess oxygen to the air.

pp. 180s and 276t, question 3

Question: With your teammates create a visual diagram, such as a concept map, that represents your current understanding of the cycling of matter through a community. Base your diagram on the two populations that you studied in this activity.

Suggested Response: As the learners create their own concept map or visual diagram, remind them to include all information that is relevant to the cycling of matter in a community....

pp. 190s and 302t, question 3

Question: Describe how the energy flows through the community, as shown in your food web.

Suggested Response: The energy flows from the sun and is converted into food energy by the producers. A portion of the energy is passed to the herbivores as they graze on the producers. This pattern continues throughout the web as indicated by the arrows.

pp. 193s and 304t, question 1

The essays in the back of the student text are referenced in the activities. For example, in the activity Building Living Systems, students are told, “The essay Metabolism Includes Synthesis and Breakdown, page E127, will help you with your explanation” (p. 181s, question 3). However, the material does not provide specific questions to guide student interpretation of the essays.

Indicator 2: Minimally met
Only occasional questions were noted that have helpful characteristics that will guide student reasoning. For example, after students have completed their work with earthworm and snail/Anacharis habitats (Exploring the Cycling of Matter in Communities) a question is asked that helps students make connections between their own ideas and the phenomena they have observed:

Question: With your teammates create a visual diagram, such as a concept map, that represents your current understanding of the cycling of matter through a community. Base your diagram on the two populations that you studied in this activity.

Suggested Response: As the learners create their own concept map or visual diagram, remind them to include all information that is relevant to the cycling of matter in a community....

pp. 190s and 302t, question 3

However, none of the questions help students make connections between their own ideas and the phenomena observed, help students make connections between their own ideas and the presented scientific ideas, or anticipate common student misconceptions.

Indicator 3: Not met
In the Explain section of Chapter 9: The Cycling of Matter and the Flow of Energy in Communities, students create a food web. The questions following this activity ask students to “Describe how the energy flows through the community, as shown in your food web” and ask “Where is the most energy available in your food web? Explain your answer” (p. 193s, questions 1 and 2). These questions focus students on the idea that energy flows in a one-way direction through the community and that energy is lost at each stage. However, the scaffolding is minimal, does not lead students to full understanding of Idea d₂, and is insufficient for the material to receive credit for meeting this indicator.

Most of the other questions/tasks that relate to key ideas are single questions or are set in a group of questions that relate to a wide range of ideas rather than being scaffolded to help students move gradually toward understanding a particular key idea. For example, the set of analysis questions following the activity Structures and Functions begins with “Explain the basic matter and energy requirements needed for a muscle to contract” (p. 155s, question 1). This question is followed by five other questions asking students about such topics as muscle fatigue; strengths and weaknesses of their leg models; advantages and disadvantages of a hydrostatic skeleton, an exoskeleton, and an endoskeleton; and how physical activity can promote fitness.

Encouraging students to think about what they have learned

Rating = Poor
The material somewhat meets the first indicator.

Indicator 1: Somewhat met
This material includes only a few instances in which students are asked to reconsider their initial ideas. For example, at the beginning of the investigation Energy in Matter, students are asked to “Discuss how you would define matter and energy and how they are related...” (p. 168s, question 1). At the end of the investigation, students are given the opportunity to revise their ideas about matter, energy, and their relationship (p. 170s). The only other instance in which students are asked to revise their ideas is after students have diagrammed a sequence of events that shows how an atom of carbon in a molecule of carbon dioxide could eventually become part of a human muscle protein. After a class discussion on this topic, students may note in their journals appropriate changes to steps in their sequences (pp. 182–183s). However, in neither case are students asked to consider how their ideas changed.

Indicators 2 and 3: Not met
The material does not engage students in monitoring how their ideas have changed.

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VI: Assessing Progress

BSCS Biology: A Human Approach provides a variety of tools to assess students’ progress at the end of instruction. The Teacher’s Resource Book (TRB) specifies “Opportunities for Summative Assessment” (TRB, p. AP-2), among which it lists “Evaluate Activities,” which appear in each chapter, “Model Chapter Assessment” (provided only for chapter 2), “Unit Assessments,” and the “Evaluate Section,” which is presented at the end of the entire program. These components of unit three—the unit that treats the key ideas related to matter and energy transformations—were examined for the first two criteria.

In addition to these components, teachers are encouraged to have students write in their portfolios at the end of each unit: “Ask the students to choose works that represent key points in their own learning process—points at which a concept became clear to them” (TRB, p. AP-3). While if done properly, students’ entries in their portfolios might demonstrate their understanding of the key ideas, this is not guaranteed; therefore, the portfolios were not taken into account in judging the sufficiency of relevant assessment tasks.

Aligning assessment to goals

Rating = Satisfactory
Since the rating scheme depends on how many assessment tasks meet both of the indicators, the report for this criterion is organized to reflect the overall rating rather than each indicator judgment.

BSCS Biology: A Human Approach provides some assessment items but not a sufficient number of items for most key ideas on the topic matter and energy transformations. (The idea that “Plants break down the sugar molecules that they have synthesized into carbon dioxide and water, use them as building materials, or store them for later use” [Idea b₁] is not treated in either the teaching or the assessment materials.)

Several questions in chapters 8 and 9 encourage students to reflect on what they have learned and use the key ideas to construct their responses. For example, the following problem is posed at the end of chapter 9:

Suppose you found yourself snowed in for the winter in a remote mountain cabin with no way of contacting the outside world. You must survive for several months with only what is on hand to eat. Aside from a small supply of canned peaches, your only resources are two 100-lb sacks of wheat and a flock of eight hens. Discuss the relative merits of the following strategies:

1. Feed the grain to the hens and eat their eggs until the wheat is gone, and then eat the hens.
2. Kill the hens at once, freeze their carcasses in the snow, and live on a diet of wheat porridge and chicken.
3. Eat a mixture of wheat porridge, eggs, and one hen a week, feeding the hens well in order to keep the eggs coming until all of the hens are killed.

pp. 198s and 310–311t, question 5

This question describes a specific situation that is likely to be motivating to most senior high students (as opposed to general questions that are heavy in terminology). The sample answer provides little guidance to teachers about the key points students should include in their answers; however, if students discuss the merits of each strategy, they will show their understanding of the key idea that “At each link in a food web, some energy is stored in newly made structures but much is dissipated into the environment as heat. Continual input of energy from sunlight keeps the process going” (Idea d₂).

In the Evaluate lesson for chapter 8, students are asked to trace “the path of a carbon atom that originates in carbon dioxide and ends up in a muscle protein in the human arm” (p. 280t), which addresses the idea that “[carbon atoms] pass...through food webs and the environment, and are combined and recombined in different ways” (part of Idea d₁). The question “Explain the flow of energy in a compost heap. What happens to the matter? What is the connection between the flow of energy and the changes in matter?” (p. 580t) addresses both Ideas d₁ and d₂.

Several questions have the potential for addressing the key ideas, but the suggested answers go far beyond what is specified in the key ideas in level of detail and/or terms. For example, an assessment question for unit three describes a scenario involving a marathon runner. Students are asked to explain how energy is conserved during the race. While the suggested response begins with the essential ideas, it then includes details that go beyond the key ideas:

Question: Picture a marathon runner at the 22 K marker (more than 13 miles into the race). He has been able to run this far because of the tremendous amount of stored energy present in his muscles and liver.

1. Trace the flow of this energy from its source to his muscles. Include answers to each of the following questions in your analysis: (9 points)
   • What was the original source of the energy that he is using to run?
   • What processes were involved in getting the energy from its source to his muscles?
   • What molecules are involved in getting the energy from its source to his muscles?

Suggested Response: The original source of the racer’s energy was the sun. The energy of sunlight was converted into the chemical energy of carbohydrates during the processes of photosynthesis and carbon fixation, and this stored chemical energy was transferred from photosynthetic organisms (producers) to the racer (a consumer) in a variable number of steps, depending on the trophic levels at which the racer ate. Digestion in the racer’s body converted the large, energy-rich carbohydrates that the racer consumed to smaller glucose molecules that could be absorbed into the racer’s bloodstream. Eventually, the energy that had originated from the sun reached the racer’s muscles and liver in the form of storage molecules.

 

2. Beginning with ATP, identify the energy conversions that are involved in each step that the runner takes. (Hint: Consider potential, kinetic, chemical, and mechanical energy at both molecular and large-scale levels.) (5 points)

Suggested Response: Movement involves the conversion of the potential energy of ATP to the kinetic energy of muscle filaments. This conversion also could be described as a conversion of chemical energy to mechanical energy. The collective kinetic/mechanical energy of the muscle filaments in a contracting muscle is then transferred to the skeleton to become the kinetic/mechanical energy of the racer’s moving leg. With each stride, some energy is converted to heat, another form of kinetic energy.

 

3. Recall from the readings that energy is conserved—that is, energy is neither created nor destroyed. How is energy conserved during the race? (Hint: ask yourself where the energy goes as the racer runs.) (6 points)

Suggested Response: Your students may find this question particularly challenging, yet unless they see that energy is not lost or destroyed, they have not seen the principle of the conservation of energy clearly. Students should answer that the racer’s kinetic energy is not lost as he runs, but is further converted to an increased kinetic energy of the air around him (as the racer moves through the air), of the ground under his feet (as the racer’s energy is transferred to molecules in the pavement), and of the sweat that absorbs some of the heat his body releases and that evaporates off his body. If your students need help with this concept, we recommend that you guide their thinking with leading questions during your oral review of the assessment. For example, you might ask them whether they can think of any evidence that suggests that a racer’s body radiates energy as he runs, and then you might ask them what happens to this energy. You also might remind them that a nail gets hot as it is pounded, and ask them whether they see any parallel between a hammer hitting a nail and a racer’s foot hitting the ground.

TRB, AP-53–54, question 12

Testing for understanding

Rating = Satisfactory
Since the rating scheme depends on how many items meet both indicators, the report for this criterion is organized to reflect the overall rating rather than each indicator judgment.

The material provides some assessment items that meet indicators 1 and 2. In order to answer questions such as those shown under the criterion Aligning Assessment to Goals, students need to understand the specified key ideas. These questions are not asking students to define specific terms, match terms and concepts, or recite material they read in the text. Rather, these questions require that students apply the information provided in the essays to specific problems or scenarios.

Using assessment to inform instruction

Rating = Poor
The material meets indicator 1.

Indicator 1: Met
BSCS Biology: A Human Approach provides formal opportunities for ongoing, formative assessment (indicated by check-mark icons in the Teacher’s Guide). In addition, teachers are encouraged to assess students informally—for example, based on “the learners’ contributions to both team and class discussions” (TRB, p. AP-4). The Teacher’s Resource Book states: “Use the learners’ responses, writing, and performance as cues to modify your instruction. For instance, if a class discussion reveals persistent misconceptions at the Explain phase...you might decide to spend a full class period in direct instruction to clarify the misconceptions” (TRB, p. AP-4). The text then identifies a variety of tools in the material that can be used to evaluate student progress to inform instruction at each phase of the instructional model.

Several of the formal tasks focus on key ideas on matter and energy transformations. For example, chapter 8 labels the following tasks as embedded assessment:

Discuss how you would define matter and energy and how they are related. Based on these definitions, identify two or three examples of evidence that support the idea that matter and energy are related.

pp. 168s/259t

Look at Figure 8.3 to see several ways that molecules can be represented. Which representation would you use to demonstrate molecular structure (atoms bonded together) to someone who did not understand that matter is organized? Explain your choice.

pp. 169–170s/261t

How does the matter in the food [your Mud City Marathon Snack] become usable energy for the body? In particular, how does it help a marathon runner keep on running?

pp. 175s/269t

Use the following short story and your understanding of energy, matter, and cellular respiration to answer the question, How can my body take in materials from a cow and make it a part of me?

Your high school girl’s basketball team has just beaten its cross-town rivals and has qualified for the state basketball tournament. To celebrate, you and two friends go to your favorite fast food restaurant and order the usual burger, fries, and soft drink. You notice that a new menu is on display, and you see that the word hamburger has been replaced by the word beefburger. After a brief discussion with your friends, you see the logic of the change. Your burger is a beefburger. This term accurately describes what you are about to eat. That realization leads to another discussion. The burger you are about to eat is rich in protein: with luck, it is not too rich in fat! This cow protein and fat will be used by your body as a source of energy and as building material for biosynthesis. The discussion centers around the question of how your body can take in materials from a cow and make it a part of you.

pp. 180–181s/278t

How does your organism use matter and energy to maintain its organization?

pp. 181s/279t

Construct a diagram or other visual aid to show a plausible set of events that could explain how a labeled carbon atom in a molecule of atmospheric carbon dioxide ends up in a human muscle protein....Write at least one paragraph that explains the sequence of events that you have diagrammed. You should include both the flow of matter and the energy sources that make these events possible.

pp. 182–183s/281–282t

Indicator 2: Not met
The material does not assist the teacher in interpreting student responses. The sample answers provide teachers with more guidance than is found in many teacher guides. For example, teachers are often alerted to the purpose of the question and to key points that students should address in their answers. However, these suggestions will not help teachers interpret student responses to diagnose what learning difficulties may remain.

Indicator 3: Not met
The material does not provide specific suggestions about how teachers can use student responses to make instructional decisions about what ideas need to be addressed by further activities.

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VII: Enhancing the Science Learning Environment

Providing teacher content support

Rating = Some support is provided.

The material provides minimal support in alerting teachers to how ideas have been simplified for students to comprehend and what the more sophisticated versions are. Background notes provide sophisticated versions of ideas for selected student text and activity sections. The advanced explanations often do not explicitly alert teachers to how ideas have been simplified for students (e.g., pp. 240–241t) or briefly elaborate on one or a few student text concepts (e.g., pp. 258–259t; p. 281t). Overall, the Background notes may be used as a selective but not a comprehensive content resource by the teacher.

The material generally provides sufficiently detailed answers to questions in the student book to help teachers understand and interpret various student responses (e.g., pp. 244–246t, Analysis, answers 2–3; pp. 308–309t, Part A, A Natural Disaster, answer 2; p. 310t, Part B, Strategies for Survival, answer 4). However, there are some limitations to the responses provided in the teacher notes, which occasionally are brief and require further explanation (e.g., p. 262t, Analysis, answer 5; pp. 301–302t, Analysis; p. 304t, Analysis, answer 2).

The material provides minimal support in recommending resources for improving the teacher's understanding of key ideas. A reference list without annotations subdivided by unit and chapter is provided at the end of the Teacher's Guide (pp. 591–603t). In addition, the Teacher's Resource Book has reference lists about biology content and general learning (pp. IG-51 to IG-53) as well as assessment strategies (pp. AP-8 to AP-9, 2.6 Resources on Assessment). While these resources might help teachers improve their understanding of the key ideas, the lists lack annotations about what kind of specific information the resources provide.

Encouraging curiosity and questioning

Rating = Some support is provided.

The material provides a few suggestions for how to encourage students' questions and guide their search for answers. At the end of some experiments, students are asked to generate questions of understanding or further inquiry (e.g., pp. 179–180s, Analysis, item 1; p. 189s, Part B, Snails and Anacharis: What Can I Learn from Them?, item 3d).

The material provides many suggestions for how to respect and value students' ideas. Teacher and student notes often stress that multiple student answers should be acceptable for questions (e.g., p. 182s, Process and Procedures, item 1; p. 279t, Part B, Energy and Matter for Organism X). Many tasks elicit students' ideas about particular concepts and issues (e.g., p. 186s, Process and Procedures, item 2; p. 261t, Step 1). In addition, students are often asked to design their own experiments (e.g., p. 151s, Process and Procedures, item 2; p. 189s, Part B, Snails and Anacharis: What Can I Learn from Them?, item 1; p. 195s, Process and Procedures, items 1–3).

The material provides many suggestions for how to raise questions such as "How do we know? What is the evidence?" and "Are there alternative explanations or other ways of solving the problem that could be better?" The material includes many tasks that ask students to provide evidence or reasons in their responses (e.g., pp. 168–169s, Process and Procedures, items 1 and 6a; p. 188s, Process and Procedures, item 2a; p. 189s, Part B, Snails and Anacharis: What Can I Learn from Them?, item 1).

The material provides many suggestions for how to avoid dogmatism. The first chapter explicitly discusses the nature of science as a durable yet dynamic human enterprise in which all people can participate (e.g., pp. 3–13s). In addition, the material discusses historical contributions (e.g., p. E115s; pp. E122–E123s) as well as the work of current scientists (p. 182s). Throughout the material, the writing avoids dogmatism by being explicitly directed to students (e.g., pp. E136–E140s) and including some narratives (e.g., p. 167s).

The material does not provide examples of classroom interactions (e.g., dialogue boxes, vignettes, or video clips) that illustrate appropriate ways to respond to student questions or ideas. However, some sense of desirable interactions may be gained from general guidelines (e.g., p. xivt, Cooperative Learning and TRB, pp. CL-1 to CL-22, Chapter 3 A Guide to Cooperative Learning) and particular directions for cooperative group activities (e.g., pp. 151–152s, 229–230t, Part A, Food for Energy and pp. 168–169s, 259–260t, Part A, Energy in Reactions).

Supporting all students

Rating = Some support is provided.

The material generally avoids stereotypes or language that might be offensive to a particular group. For example, photographs include a diverse cultural mix of students and adults (e.g., pp. 138–140s, 181s, 194s). In a few instances, the subject matter may be offensive to students (e.g., TRB, pp. OA-17 to OA-21, Elaborate, Optional Activity: Of Cannibals and Calories).

The material provides select illustrations of the contributions of women and minorities to science and as role models. These contributions are integrated throughout the material in the student text and tasks. For example, one essay contrasts the wastes produced by different organisms. Details of the lives of the earliest Anasazi Indians provide an example of people producing little waste that is easily recycled (pp. E129–E131s). In a related task where students analyze matter and energy cycling through food webs, they are asked about the Anasazi Indians' use of matter (p. 192s, item 3b; p. 193s, Analysis, item 4).

The material suggests multiple formats for students to express their ideas during instruction and assessment, including individual journal writing (e.g., pp. 186-187s, Analysis), pair work (e.g., pp. 197–198s, Part B), cooperative group activities and laboratory investigations (e.g., pp. 171–175s), whole class discussions (e.g., p. 166s, item 2), essay questions (e.g., p. 183s, Process and Procedures, item 2; p. 198s, item 5 ), oral reports (e.g., p. 196s, Analysis, item 1), written reports (e.g., p. 152s, item 9), research projects (e.g., p. 199s, item 1), visual projects (e.g., p. 182s, item 1), and skits (e.g., p. 199s, item 2). For a few activities, the material provides alternatives for the same task (e.g., p. 181s, Part B).

The material does not routinely include specific suggestions about how teachers can modify activities for students with special needs. However, the student text, Teacher's Guide and Teacher's Resource Book provide some additional activities for students. Within each chapter, there are Further Challenges (e.g., p. 171s) and Extensions (e.g., p. 304t) in which students may further study a related interest. The Teacher's Resource Book includes a few optional extension activities similar in complexity to those in the student text (e.g., pp. OA-33 to OA-34, Engage/Explore, Optional Activity: Field Observation).

The material provides some strategies to validate students' relevant personal and social experiences with scientific ideas. Some text sections relate specific personal experiences students may have had to the presented scientific concepts (e.g., pp. E96–E98s). In addition, some tasks (e.g., pp. 190–193s, pp. 292–295t) ask students about particular personal experiences they may have had or suggest specific experiences they could have. However, the material rarely encourages students to contribute relevant experiences of their own choice to the science classroom. Overall, the tasks are well integrated with students' personal and social experiences with scientific ideas.

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