AAAS Project 2061 Textbook Evaluations

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BSCS Biology: An Ecological Approach. Kendall/Hunt, 1998

Matter and Energy Transformations: Instructional Analysis

I: Providing a Sense of Purpose

Conveying unit purpose

Rating = Fair
The material meets indicators 1, 2, and 5 but does not meet indicators 3, 4, and 6.

Indicator 1: Met
The material provides an explicit statement of purpose for sections and chapters. For example, Section One: The World of Life: The Biosphere states, "Section One examines the relationships between some familiar living things and begins to explain just how profound the effects of human activities can be” (p. 3s). And Chapter 4: Matter and Energy in the Web of Life states, “This chapter examines...molecules and investigates some of the characteristics of matter and energy” (p. 71s).

Indicator 2: Met
Prior to the explicit statement of purpose, sections and chapters include an introductory paragraph that brings some clarity to the purpose statements, particularly the chapter purpose statements. For example, Chapter 4: Matter and Energy in the Web of Life states that

All living things are tied together by their need for matter and energy. Using energy from the sun and absorbing matter from the surrounding soil and air, producers, such as green plants, make their own food. Consumers, on the other hand, must obtain their matter and energy from other organisms. Humans, for instance, eat plants and animals to get their matter and energy. This matter and energy (food) is made up of biological molecules—the molecules that are found in all living things. We eat the molecules of plants and animals and then rearrange them to make our own molecules. This chapter examines these important molecules and investigates some of the characteristics of matter and energy.

p. 71s

Indicator 3: Not met
There is no interesting question posed or problem to be solved. The stated purposes are not likely to be interesting or motivating to students. While the paragraphs are accompanied by a photograph and related questions that “encourage student interaction with the text” (p. T4), these accompanying items are not linked to the stated purpose. For example, the photograph at the beginning of Chapter 4: Matter and Energy in the Web of Life is accompanied by the question “What happened to this area about three weeks before this photo was taken?” (p. 71s).

Indicator 4: Not met
Although questions are provided at the beginning of each chapter and section—both in the student text accompanying the introductory photograph and in the Knowledge Check part of the teacher notes—none focus on the purpose of the chapter or section.

Indicator 5: Met
Since each purpose statement lists the major topics in the chapter, lessons are consistent with the stated purpose.

Indicator 6: Not met
Although each chapter ends with a summary of the chapter contents, none of the summaries explicitly return to the stated purpose.

Conveying lesson/activity purpose

Rating = Poor
The material meets indicator 1 and somewhat meets indicator 2. No other indicators are met.

Indicator 1: Met
The material uses a few strategies to convey the purpose of readings and investigations to students. Guidepost questions—for example, “What is the source of energy for living organisms and how is it used?” (p. 75s) and “How are carbon-containing molecules important to living things?” (p. 78s)—frame major sections. It is worth noting that Guidepost questions frame only some of the reading assignments suggested in the teacher’s guide. For example, the Strategies section of the teacher’s guide for chapter 4 suggests that the chapter be subdivided into six reading assignments: “Give short assignments, as follows: Sections 4.1–4.2, 4.3, 4.4–4.6, 4.7–4.9, 4.10–4.13, and 4.14” (p. T47). However, Guidepost questions are provided at the beginning of only three of these reading assignments: Sections 4.1–4.2 (p. 71s), 4.4–4.6 (p. 75s), and 4.7–4.9 (p. 78s).

Section headings such as “Photosynthesis Is the Source of Your Energy” (p. 75s) and “Carbohydrates Are Used for Energy, Storage, and Building” (p. 79s) summarize the main point of smaller sections. For investigations, the purpose is found in the introduction (e.g., “In this investigation, you will observe tests for specific compounds and then use those tests to determine which compounds are found in ordinary foods” [p. 89s]).

Indicator 2: Somewhat met
Some of the Guidepost questions and section headings avoid technical terms, as in the questions “How are carbon-containing molecules important to living things?” (p. 78s) and “What is the source of matter for living things, and what happens to the matter?” (p. 84s). Others are less likely to be comprehensible to students, using vague phrases and terms, as in the question “How are matter and energy related in the biosphere?” (p. 71s).

Indicator 3: Not met
Students are not asked to think about the purpose of the readings or the lab activities. No directions are given to the student to read, think about, or discuss the Guidepost questions, and no suggestions are given to the teacher to have students read and think about them (e.g., on p. T4, where the role of the Guidepost questions is given).

Indicator 4: Not met
The provided purposes do not convey how the readings or lab activities are related to the unit or chapter purpose.

Indicator 5: Not met
The material does not engage students in thinking about what they have learned so far and what they need to learn next.

Justifying lesson/activity sequence

Rating = Fair
The material somewhat meets indicator 1 but does not meet indicator 2.

Indicator 1: Somewhat met
For each chapter, the Strategies section of the teacher’s guide suggests a sequence of readings and investigations. For example, the following sequence is suggested for Chapter 4: Matter and Energy in the Web of Life (see pages T47–T48):

Investigation 4.1: Organisms and pH

• Students compare the effects of adding HCl and NaOH to tap water, a buffer, and several biological materials

Text 4.1–4.2

• Matter Is Made of Atoms (deals with elements and compounds, parts of the atom, charges on ions, and chemical bonds)
• Chemical Reactions Are Essential to Life (deals with types of chemical reactions, ionization, the pH scale, and catalysts and enzymes)

Text 4.3

• Energy Makes Work and Order Possible (gives examples of energy-requiring processes)

Text 4.4–4.6

• Photosynthesis Is the Source of Your Energy (gives overview of transformation of light energy to chemical energy in green plants)
• Energy is Released as Food Is Broken Down (gives overview of cellular respiration)
• Energy Is Used in Small Packets (describes role of ATP as currency of energy transfer)

Investigation 4.2: Compounds in Living Organisms

• Students test various foods for the presence of basic components (protein, glucose, starch, vitamin C, chloride, and lipid)

Text 4.7–4.9

• Carbon Is Found in All Living Things (describes ability of carbon to form a vast number and variety of organic compounds, mentions the classes of molecules found in all organisms, and states that we survive by eating animals or plants and rearranging their molecules into our own)
• Carbohydrates Are Used for Energy, Storage, and Building (describes the formation of carbohydrates from simple sugars and gives examples)
• Lipids Are Efficient Energy Storage Compounds (describes the formation of lipids from glucose and gives examples)

Investigation 4.3: Enzyme Activity

• Students examine the effects of enzyme concentration, temperature, and pH on the activity of the enzyme catalase

Text 4.10–4.13

• Muscles, Enzymes, and Many Cell Parts Are Made of Protein (describes formation from amino acids)
• Enzymes Catalyze Cell Reactions (describes how enzymes work)
• Nucleic Acids Control the Activities of the Cell (describes DNA, RNA, and their basic composition and structure)
• Plants Make and Use Carbon-Containing Sugars (describes how plants use the sugar molecules they make in photosynthesis)

Text 4.14

• Carbon Cycles Within an Ecosystem (describes carbon cycle)

There is logic evident in the way activities and readings are sequenced but not in the way topics in the text are sequenced. Student investigations generally relate to some aspect of the subsequent readings. However, the sequence of topics in the text seems to move back and forth between matter and energy in a way that may be confusing to students. For example, even though the text states that “[u]nderstanding matter is fairly easy. You can see it, you can touch it, and you can weigh it. Understanding energy is more difficult” (p. 74s), it begins by presenting the energy story (sections 4.4–4.6) and then moves to the matter story (sections 4.7–4.14). In the early sections of the chapter, fundamental ideas about matter were introduced before ideas about energy. It would have made more sense if the chapter had first introduced fundamental ideas about matter, moved to applying the ideas about matter to living organisms, and then introduced fundamental ideas about energy just before applying the ideas to living organisms and ecosystems.

Indicator 2: Not met
The material does not provide a rationale for its sequence of activities. The Strategies section does include suggestions for the use of investigations—for example, “Begin the chapter with Investigation 4.1 and use the remaining two investigations to break up the reading assignments and to illustrate the ideas in the previous sections” (p. T47) and “Let the activities drive this chapter....begin the chapter with Investigation 5.1...the first [reading] assignment [is] a review of that investigation” (p. T52). However, these few suggestions stop far short of providing a “story line” for the information in the chapter.

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II: Taking Account of Student Ideas

Attending to prerequisite knowledge and skills

Rating = Poor
The material minimally meets indicators 4 and 5 but does not fully meet either indicator.

Indicator 1: Not met
The material does not typically alert teachers to important prerequisite knowledge or skills. Though the teacher’s guide mentions that students “need some understanding of chemistry to comprehend such topics as cellular respiration, photosynthesis, and the structure of nucleic acids” (p. T47, Strategies), no specific prerequisite ideas are mentioned.

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 the specific ideas or skills that are being assumed.

Indicator 4: Minimally met
The material treats three out of eight prerequisites identified from strand maps collected in Atlas of Science Literacy (AAAS, 2001), mostly by asserting the prerequisite ideas in the text. The text states the prerequisite idea that “Energy can only change from one form into another” in an Applications question at the end of Chapter 19: The Flowering Plant: Maintenance and Coordination:

Energy can be changed from one form to another, but it cannot be created or destroyed. Give several examples from this chapter, or any part of the text, in which energy is changed from one form to another.

p. 512s, Applications, item 7

The text states the prerequisite idea that “Carbon and hydrogen are common elements of living matter” in the context of Section 1.5: Matter Is Used to Build Living Things and represents the idea on a pie chart:

Of the more than 100 different elements found on the earth, only about 30 are used in the makeup of organisms. Most of these elements, such as the hydrogen found in a water molecule and the carbon found in the carbon dioxide of the air, are very common. Figure 1.12 shows the proportions of elements in humans.

p. 12s

The text states the prerequisite again in Section 4.1: Matter Is Made of Atoms: “Four elements—carbon, oxygen, hydrogen, and nitrogen—are common to all living systems” (p. 71s).

The text presents the prerequisite idea that “Food provides the molecules that serve as fuel...for all organisms” and includes an activity that demonstrates that food contains energy. The student text states the idea in the context of human digestion:

The food you had for lunch may serve one of two purposes. First, it can provide usable energy for life functions. Second, the breakdown of the food can provide molecules to be reassembled into larger molecules that build or repair cells in the body.

p. 384s

An investigation at the end of the chapter demonstrates that food contains energy (pp. 393–396s). The introduction to Investigation 15.1: Food Energy states that “All foods contain energy, but the amount of energy varies greatly from one food to another” (p. 393s). Students burn peanuts and walnuts, using a calorimeter to measure the amount of energy released by each food sample. The teacher notes state, “You may wish to discuss the idea that the energy released from foods is associated with a corresponding chemical change in the food itself” (p. 393t).

However, other prerequisites—for example, “Arrangements of atoms have chemical energy,” “Different amounts of energy are associated with different configurations of atoms....,” and the prerequisite about matter conservation—are not even stated.

Indicator 5: Minimally met
The text makes connections between a few prerequisites and key ideas about matter and energy transformations, mainly in the text. Section 1.5: Matter Is Used to Build Living Things makes a connection between matter transformation in photosynthesis (Idea a₁) and the prerequisite idea that “Carbon and hydrogen are common elements of living matter.” The text first states the prerequisite and represents it on a pie chart and then states the key idea (p. 12s). By putting the two ideas in close proximity, the text makes it possible for students to see the connection between them.

The text explicitly connects the prerequisite that “Food provides the molecules that serve as...building materials for all organisms” to the breakdown and reassembly of food molecules by other organisms (Idea c₁). In the context of describing human digestion, the text states the prerequisite and explains why breakdown and reassembly are needed:

Three types of molecules are used in all living cells as building materials and as sources of energy—carbohydrates, proteins, and fats (lipids). Although the food you eat must supply these molecules, your body cannot use the molecules directly from the food. Just as an old brick building can be demolished and the bricks used to construct a patio or a fireplace, so the human body tears food molecules apart and forms useful building blocks.

p. 375s

The text also relates this prerequisite to energy transformations in photosynthesis (Idea a₂) and respiration (Idea c₂). Just before introducing ideas about energy transformations in photosynthesis and respiration (p. 11s), the text notes that the activities of an organism require energy, asks where the energy comes from, notes that “[c]hemical energy is found in the structure of the molecules that make up the meat and the potatoes [in a hamburger and french fries],” and then frames its presentation of the key ideas with a question: “The hamburger that contains chemical energy came from a cow; cows eat only grasses and grains. A grass plant and a potato do not eat other organisms, so where do they get their energy?” (p. 10s).

The connections are made through the use of the same examples—hamburgers and potatoes.

One of the Applications questions at the end of Chapter 19: The Flowering Plant: Maintenance and Coordination involves students in making a connection between the prerequisite that “Energy can only change from one form into another” and key ideas about energy transformation:

Question: Energy can be changed from one form to another, but it cannot be created or destroyed. Give several examples from this chapter, or any part of the text, in which energy is changed from one form to another.

Suggested Response: Plants convert light energy into chemical energy during the process of photosynthesis, and some of this chemical energy is lost as heat energy during cellular respiration....

pp. 512s and T106, Applications, item 7

Despite these connections, opportunities were missed to make connections between key ideas about energy transformation and their prerequisites. For example, the text could have connected the prerequisite that “Arrangements of atoms have chemical energy” to energy transformation in photosynthesis but failed to do so. The text states that “Chemical energy is found in the structure of the molecules that make up the meat and the potatoes” (p. 10s), but does not state the prerequisite itself. Similarly, a figure that compares the energy released during burning and cellular respiration (p. 77s, Figure 4.10) could have been used to connect the prerequisite that “An especially important kind of reaction between substances involves combination of oxygen with something else—as in burning or rusting” and cellular respiration (Idea c₂). However, the prerequisite idea is not presented. And, the prerequisite on the conservation of matter is neither treated nor connected to the repeated cycling of elements through ecosystems (Idea d₁).

Alerting teachers to commonly held student ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
Even though research indicates that students have a number of difficulties with the ideas related to matter and energy transformations, the teacher notes mention only one. Teachers are told, “You may find students saying that animals use respiration but that plants use photosynthesis to obtain energy” (p. 76t and a similar statement on p. 492t). However, the teacher note is followed by a statement of the correct idea—“Through photosynthesis, plants build up food reserves. These food reserves then are broken down by respiration to release energy for the plant” (p. 76t)—rather than by an explanation of the misconception. Teachers are not alerted to any of the following commonly held student ideas that may interfere with students learning the key ideas:

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).

While the References list for chapter 19 includes an article that could provide helpful information—“Eisen, Y., and R. Stavy. ‘Students’ Understanding of Photosynthesis.’ American Biology Teacher (April 1988): 208–12” (p. T105)—the list presents 12 references in all and gives no suggestion that this particular article alerts teachers to commonly held student ideas.

In addition, a note to the teacher in Chapter 2: Populations indicates that “The terms food and nutrient are used in different ways by animal and plant biologists” (p. 34t) but does not indicate the difficulty this may pose for students.

Indicator 2: Not met
As described in the analysis of the previous indicator, the material does not explain the commonly held student idea that it mentions.

Assisting teachers in identifying their students’ ideas

Poor
The material minimally meets indicator 1 but meets no other indicators.

Indicator 1: Minimally met
Although teacher notes at the beginning of each chapter include Knowledge Check questions, very few of these questions are relevant to the key ideas. For example, questions such as “What is a chemical reaction?” and “What are enzymes?” (p. 71t), “How do ‘junk’ foods differ from other foods?” and “Why is what you eat important to you?” (p. 373t), and “What are plant hormones, and how do they affect plant growth and development?” and “How do plants respond to environmental stimuli?” (p. 489t) relate to other ideas. Those questions that are relevant lack the specificity needed to help teachers diagnose students’ difficulties with key ideas about matter and energy transformations. For example, the questions “What is energy, and where does it come from?” (p. 71t) and “How does your body use the foods you eat?” (p. 373t) are too broad and could elicit responses that have no connection to the key ideas being diagnosed. More specific questions like “What are the materials and products of photosynthesis?” (p. 489t) could be used as the first question in a series, but without knowledge of commonly held student ideas, teachers have no guidance in designing such questions. The Guidepost questions in the student text do provide some potentially useful questions, but their intent is to “arouse student interest and curiosity and help students identify important ideas” (p. T4), not to help teachers find out what students already know. There is no suggestion that students are to respond to these questions.

Since there are few relevant questions, the subsequent indicators are not met.

Indicator 2: Not met
While questions are written in clear, non-technical language, too few are relevant to the key ideas about matter and energy transformations.

Indicator 3: Not met
The teacher’s guide states that “Annotations in the Teacher’s Edition include a list of major concepts and questions that will help you assess students’ prior knowledge” (p. T1). However, too few of the Knowledge Check questions focus on key ideas about matter and energy transformations.

Indicator 4: Not met
The material does not include questions or tasks that ask students to make predictions or give explanations of phenomena. Knowledge Check questions do not specifically ask for explanations. For example, the question “How do humans fit in the world?” (p. 5t) could elicit a brief response that lacks an explanation and is not likely to provoke responses that give teachers sufficient indication of underlying student ideas.

Indicator 5: Not met
The material provides no suggestions to teachers for probing for deeper understanding or interpreting student responses.

Addressing commonly held ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The material does not explicitly address commonly held ideas. In the one instance where teachers are alerted to a commonly held idea (pp. 76t and 492t), the teacher’s notes simply state the correct idea. Furthermore, several figures and statements made in the material could reinforce erroneous commonly held student ideas. For example, Figure 4.11 (p. 77s) could lead students to conclude that plants do not carry out cellular respiration—that is, they do not get their energy from sugars, use O₂, or release CO₂—and the equation for respiration on page 378s could reinforce the commonly held student idea that living things can convert matter into energy or energy into matter.

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 include 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.

Though the material provides six phenomena that could be used to support the key ideas about matter and energy transformations—blocking stomates reduces starch production in leaves (pp. 508–510st, Investigation 19.2), a burning peanut gives off heat (pp. 393–396st, Investigation 15.1), the action spectrum of photosynthesis correlates well with the absorption spectrum of chlorophyll (p. 491s, Figure 19.3), seeds are good sources of food (pp. 94s and T48, Applications question 7 and Suggested Answer 8), you lose weight if you do not eat (pp. 401s and T88, Applications question 9 and Suggested Answer 9), and most communities have more producers than consumers (p. 54s)—only one of them is explicitly connected to a key idea.

None of the investigations provided are used to support the key ideas. For example, relevant to the key idea that “Plants make sugar molecules from carbon dioxide (in the air) and water” (Idea a₁), Investigation 19.1: Gas Exchange and Photosynthesis (pp. 506–508s) involves students in observing the effects of covering upper or lower leaf surfaces with petroleum jelly on photosynthetic activity. This phenomenon of photosynthetic activity being disrupted could be used to make the idea plausible that leaves can only make sugar (and convert it to starch) if carbon dioxide is present. However, the phenomenon is not explicitly linked to the idea. Carbon dioxide, sugar molecules, and water are never mentioned. In the one question that could be used to make the link—“If you use these tests [iodine tests] as an indication of photosynthetic activity, what are you assuming?” (p. 508s, Discussion question 2)—the suggested response in the teacher’s guide (p. 508t) refers only to starch accumulation or the lack of starch as an indicator of photosynthesis (not to where the elements that make up the starch [sugar] came from).

Similarly, a phenomenon that could have been used to support the idea that “Plants transfer the energy from light into ‘energy-rich’ sugar molecules” (Idea a₂) is not explicitly linked to this idea. Investigation 19.2: Photosynthetic Rate (pp. 508–510s) involves students in investigating the effects of light intensity and pH on the rate of photosynthesis of Elodea. The most relevant discussion questions do not focus on energy transformation:

Use the change in the pH that occurs at the three light intensities you tested to determine the effect of light intensity on the rate of photosynthesis. Does your data support your hypothesis?

Use the change in pH with the three colors (red, blue, and green) to determine the effect of light color on the rate of photosynthesis. Do your data support the hypothesis that you constructed?

p. 510s, Discussion questions 7 and 8

Even the burning peanut investigation, which could have been used to support ideas about energy transformation in plants (Idea b₂) and other organisms (Idea c₂) was not explicitly linked to these key ideas. Investigation 15.1: Food Energy (pp. 393–396s) involves students in determining the amount of energy released when a given mass of a peanut and a walnut burns. The emphasis of the investigation is on energy transformation (chemical energy to heat) but questions—“Which of the two foods you tested seems to be the better energy source?,” “Why might some foods with fewer kcals be better energy sources than other foods with more kcals?,” and “What was the original source of energy in all the foods tested?” (p. 396s, Discussion questions 5, 6, and 7)—focus on energy sources rather than transformations.

The only phenomenon that was explicitly linked to the key ideas was found in an Applications question:

Question: Why do you lose weight rather than remaining the same weight if you do not eat?

Suggested Response: All living cells require a source of energy to keep them alive. When a person does not eat, there is no incoming source of energy. To obtain the required energy, the body will break down storage compounds. As this is done, the body loses weight.

pp. 401s and T88, Applications, item 9

The Applications question is linked to the idea that “Other organisms break down the consumed body structures to sugars and get energy to grow and function by oxidizing their food....” (part of Idea c₂).

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. None of the first hand experiences are linked to the key ideas about matter and energy transformations. The one phenomenon that is linked (if you do not eat, you lose weight [p. 401s, Applications question 9]) is likely to be vicarious for students. However, one phenomenon is not sufficient for the set of key ideas.

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IV: Developing and Using Scientific Ideas

Introducing terms meaningfully

Rating = Fair
The material somewhat meets both indicators.

Indicator 1: Somewhat met
The material includes all of the terms related to the key ideas but makes few links to relevant experiences. For example, the term “photosynthesis” is presented with only a minimal link to a relevant experience—that plants grow but don’t eat:

A grass plant and a potato do not eat other organisms, so where do they get their energy?

All green plants grow in light. In the process of photosynthesis, plants absorb light energy and convert it to the chemical energy found in sugars. The sugars formed by photosynthesis provide food for the plant. The plant then can use the energy in the sugars to grow and reproduce....

pp. 10–11s

Sometimes, the material does include a helpful analogy when introducing abstract terms. For example, ATP is introduced as the “small change” of energy transfer:

If you had one $100 bill, you might find it difficult to buy small things such as a hamburger, a pack of notebook paper, or a comb. It would be much easier if you had 100 $1 bills. So, too, with the energy in a cell. The large amounts of energy in food molecules are converted into “small change.” This “small change” is the chemical energy stored in compounds such as ATP....

p. 78s

However, as described under the subsequent criterion Representing Ideas Effectively, the representations often are incomprehensible and not likely to provide students with a relevant experience.

Indicator 2: Somewhat met
The material presents the flow of matter and energy topic in four chapters that appear to be meant to spiral from most basic to most advanced knowledge. Chapter 1 introduces basic ideas about matter and energy flow in ecosystems and the related terms “producers,” “consumers,” “decomposers,” and “food web” (pp. 8–9s). No excess terms are used in this chapter. Chapter 4 relates the flow of matter and energy to chemical concepts and introduces terms like “catalysts,” “enzymes,” “ATP,” and “proteins” (pp. 73–79s) but adds several terms not needed for literacy—“ionization,” “pH,” “lipids,” “nucleic acids,” “fatty acids,” “glycerol,” “triglyceride,” “cholesterol,” and amino acids “glycine” and “alanine” (pp. 73–81s). Chapter 15 considers digestion and energy release from food in human organisms and adds terms like “glycolysis,” “Krebs cycle,” “electron transport system,” “pyruvic acid,” “acetyl coenzyme A,” “oxaloacetic acid,” and “glycerol” (pp. 378–382s)—all of which go well beyond science literacy. Similarly, chapter 19 goes into details of photosynthesis, including the terms “Calvin cycle,” “nicotinamide adenine dinucleotide phosphate,” and “thylakoid membrane” (pp. 491–493s). Taken as a whole, the material includes an enormous number of terms. However, most occur in the text or figures of later chapters where more advanced material is presented.

It is worth noting that neither the Concept Review questions at the end of major sections nor the Applications or Problems at the end of chapters focus on the meaning of terms. And the chapter summaries refrain from using technical terms.

Representing ideas effectively

Rating = Poor
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.

The material includes hardly any representations that meet all the indicators (comprehensible, accurate, and explicitly linked to the real thing). Hence, the representations will not serve to clarify the key ideas.

Though the material uses more than 20 representations to convey key ideas about matter and energy transformations, most of them are likely to be incomprehensible to students who do not already understand the ideas. For example, Figures 1.10 (p. 11s) and 1.13 (p. 13s) in chapter 1 and Figures 4.9 (p. 76s), 4.10 (p. 77s), and 4.11 (p. 77s) in chapter 4 all use arrows to represent something related to matter and energy; but it is not clear what the arrows in each figure mean. And the use of color for arrows is inconsistent from one figure to the next: orange arrows represent heat in Figures 1.10, 4.10, and 4.11 but matter in 4.9; green arrows represent other forms of energy in Figure 1.10 but the direction of the reaction in 1.11 and 4.10b; Figure 4.10a uses black arrows to represent heat and light. Furthermore, the incompleteness of the figures may reinforce student misconceptions. For example, Figure 1.10 shows “chemicals (carbon dioxide, oxygen, nitrogen, and other elements)” as coming from decomposers but not from consumers or producers (p. 11s) and Figure 4.11 may lead students to conclude that cellular respiration is a process carried out by an animal but not by plants (p. 77s). Similarly, Figure 4.24 (p. 86s) attempts to illustrate the variety of ways plants use the sugars they make in photosynthesis but links only biological molecules to biosynthesis, not growth and storage. For all of these figures, the text neither provides a legend that adequately explains what the figure does and does not represent nor effectively links the figure to the key ideas.

Some of the representations are inaccurate. For example, the equation shown on page 378s—C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy—implies that energy is not conserved.

The material does use one nice analogy to illustrate the use and reuse of molecular building blocks—“Just as an old brick building can be demolished and the bricks used to construct a patio or a fireplace, so the human body tears food molecules apart and forms useful building blocks” (p. 375s). However, this example is not typical of the material.

Demonstrating use of knowledge

Rating = Poor
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 about matter and energy transformations to explain phenomena.

Indicator 2: Not met
The material provides no performances.

Indicator 3: Not met
The material provides no performances that could be identified as demonstrating the use of knowledge.

Indicator 4: Not met
The material presents no running commentary or criteria for judging a good explanation.

Providing practice

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

The material does not provide a sufficient number or variety of tasks across the set of key ideas. The material provides a couple of practice tasks each for three of the key ideas, a single practice task for one of the ideas, and no practice tasks at all for the other five key ideas. For example, for the idea that “Plants transfer the energy from light into ‘energy-rich’ sugar molecules” (Idea a₂) the material provides the following tasks:

Question: Why do almost all food chains begin with photosynthetic organisms of some type?

Suggested Response: All living things require a source of energy. Only photosynthetic organisms can convert light energy into the chemical energy that can be used as food by consumers. (You may want to introduce other food chains such as those near deep sea vents in which heat-using microorganisms are the producers.)

pp. 23s and T37, Applications, item 8

Question: Energy can be changed from one form to another, but it cannot be created or destroyed. Give several examples from this chapter or any part of the text, in which energy is changed from one form to another.

Suggested Response: Plants convert light energy into chemical energy during the process of photosynthesis, and some of this chemical energy is lost as heat energy during cellular respiration. Also, when an organism moves, chemical energy is converted into kinetic energy.

pp. 512s and T106, Applications, item 7

Similarly, the material provides two practice tasks 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, including some energy stores” (Idea c₁):

Question: The proteins in the cells of a wheat plant are different from the proteins in your cells. How can the differences be explained? What must happen when you use wheat as a nutrient for the formation of your proteins?

Suggested Response: Wheat enzymes put amino acid building units in sequences of [sic] characteristic of wheat physiology. Through digestion, wheat proteins are reduced to amino acids, and these then are synthesized into new proteins characteristic of human physiology.

pp. 94s and T48, Applications, item 2

Question: A quotation from the Bible says that “all flesh is grass.” In terms of the food you eat, what does this mean?

Suggested Response: Directly, or indirectly, all human food comes from plants (as in grass). The biological molecules in the grass plants or whatever food one eats are broken down and converted into the biological molecules of humans.

pp. 401s and T88, Applications, item 10

The material also provides two practice tasks for 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):

Question: Are animals needed for carbon to cycle within a community? Explain.

Suggested Response: No. Plants can return carbon to the atmosphere through cellular respiration and then recapture it through the process of photosynthesis. Animals exhale carbon dioxide to the air, but the cycle would continue without them.

pp. 94s and T48, Applications, item 5

Question: The proteins in the cells of a wheat plant are different from the proteins in your cells. How can the differences be explained? What must happen when you use wheat as a nutrient for the formation of your proteins?

Suggested Response: Wheat enzymes put amino acid building units in sequences of [sic] characteristic of wheat physiology. Through digestion, wheat proteins are reduced to amino acids, and these then are synthesized into new proteins characteristic of human physiology.

pp. 94s and T48, Applications, item 2

The first of these questions also gives students a chance to practice 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), but no other practice tasks are provided for this idea.

Furthermore, no practice tasks are provided for the other key ideas. While the material includes a few other tasks that could be used to practice key ideas, the suggested answers in the teacher’s guide give no indication that the questions address the substance of the key ideas.

All of the tasks shown above are novel. However, the material does not provide familiar tasks or a sequence of questions or tasks in which the complexity is progressively increased. As a result, students have no preparation for the novel tasks. 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 = Poor
The material meets no indicators. No instances were found in which students were encouraged to express, clarify, or justify their ideas.

Indicator 1: Not met
The material does not routinely encourage students to express their ideas. No instances were found in which students were asked to express their ideas about key ideas in the matter and energy transformations topic.

Indicator 2: Not met
The material does not encourage students to clarify, justify, or represent their ideas.

Indicator 3: Not met
The material does not provide opportunities for each student (rather than just some students) to express their ideas.

Indicator 4: Not met
The material does not provide specific suggestions to help the teacher provide explicit feedback to students or include text that directly provides students with feedback.

Indicator 5: Not met
The material does not include suggestions on how to diagnose student errors, explanations about how these errors may be corrected, or recommendations for how students’ ideas may be further developed.

Guiding student interpretation and reasoning

Rating = Poor
The material somewhat meets indicator 1 but does not meet indicators 2 and 3.

Indicator 1: Somewhat met
The material provides specific and relevant questions for readings, but the questions provided at the end of investigations are not relevant to the key ideas. The student text includes Concept Review questions at the end of each major text section, some of which relate to the key ideas about matter and energy transformations. For example, the following Concept Review questions are provided at the ends of sections in chapter 1 and chapter 4:

How are light and chemical energy related in photosynthesis?

How does matter get from the soil and air to animals?

How is the flow of energy through a community different from that of matter?

Explain why energy flows and chemicals cycle through food webs.

p. 13s, items 2–4 and 6

What are the two products of photosynthesis?

How are the reactions of photosynthesis and cellular respiration similar?

How are they different?

p. 78s, items 2 and 3

Of the four ways a plant uses the sugars it makes, which is the only way that does not add material to the plant?

How are producers, consumers, and decomposers involved in the carbon cycle?

p. 87s, items 1 and 2

The teacher’s guide includes corresponding numbers in the inner margins of the text where the answer to each question is provided (for example, see pages 11–12t and page 76t).

While some of the investigations could be used to support key ideas—for example, Investigation 15.1: Food Energy, Investigation 19.1: Gas Exchange and Photosynthesis, and Investigation 19.2: Photosynthetic Rate—the discussion questions rarely provide the link between the phenomena examined and key ideas. For example, Investigation 15.1 deals with food energy stored in plant tissue. However, discussion questions—“Which of the two foods you tested seems to be the better energy source?,” “Why might some foods with fewer kcals be better energy sources than other foods with more kcals?,” and “What was the original source of energy in all the foods tested?” (p. 396st)—do not make a connection between the common food materials tested and the key ideas 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) and “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). Investigation 19.1 (pp. 506–508st) and text in chapter 18 (p. 464s) relate the number of stomates present in a leaf to gas exchange and photosynthesis but do not establish a link to the idea that plants convert CO₂ and H₂O to sugars (Idea a₁).

Indicator 2: Not met
The questions do not have helpful characteristics such as helping students to relate their experiences with phenomena to presented scientific ideas, helping students to make connections between their own ideas and the phenomena observed, helping students to make connections between their own ideas and the presented scientific ideas, or anticipating common student misconceptions. As indicated in the teacher’s guide, the Concept Review questions are “a series of recall questions” (p. T4) and the answers to them can always be found in the preceding text.

Indicator 3: Not met
The material provides no sequenced questions to guide students stepwise toward complex ideas.

Encouraging students to think about what they have learned

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
No instances were found in which students are given an opportunity to revise their initial ideas.

Indicators 2 and 3: Not met
No instances were found in which students are asked to consider how their ideas have changed during instruction.

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VI: Assessing Progress

BSCS Biology: An Ecological Approach provides a test bank with items for each chapter and the teacher’s guide indicates that the Applications questions can also be used to test students’ ability to synthesize knowledge. For the first two criteria, these components were examined for chapters 1 and 4—the chapters that treat the key ideas related to matter and energy transformations.

Aligning assessment to goals

Rating = Fair
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: An Ecological Approach provides ten assessment items for one of the key ideas but provides no assessment items for most of the other ideas. The relevant items in the test bank (shown below) mostly assess understanding of 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):

Which of these sentences describes the pathway of energy through living things in their environment?

1. chemical energy → light energy → heat
2. heat → chemical energy → light energy
3. heat → light energy → chemical energy
4. light energy → chemical energy → heat

Test Item File Manual, p. 5, item 15

A farmer started colonies of rats and mink hoping to feed the rats to the mink and the skinned mink to the remaining rats, thereby getting mink skins for nothing. Is this possible?

1. yes, because the system would be in balance
2. yes, because energy lost feeding rats to mink would be recovered by feeding mink to rats
3. no, because carnivores cannot feed on each other
4. no, because much of the food energy is lost as heat

Test Item File Manual, p. 6, item 17

If you were marooned on a bare island with only a limited amount of corn and chickens to eat, what would be your best survival strategy?

1. eat the chickens, then the corn
2. eat the corn, then the chickens
3. feed the corn to the chickens, and then eat the chickens
4. feed the corn to the chickens, eat the chickens’ eggs, and then eat the chickens

Test Item File Manual, p. 6, item 18

What eventually happens to most of the energy that enters a food web?

1. it is converted to chemical energy
2. it is lost as heat
3. it is recycled by decomposers
4. it is reused during photosynthesis

Test Item File Manual, p. 7, item 19

Which best describes the path that energy takes as it moves through a community?

1. it is converted to heat as it passes from one organism to the next
2. it is converted to matter by photosynthesis and stored as plant material
3. it is cycled and reused by organisms in food chains
4. it is used up by organisms in food webs

Test Item File Manual, p. 7, item 20

In order for a biological community to survive, energy must be supplied. In what form is this energy lost?

1. chemical
2. electrical
3. light
4. heat

Test Item File Manual, p. 7, item 21

Through which pathway would the most energy be available to humans? (see diagram CH03R011 on page 86 of Test Item File Manual)

1. I
2. II
3. II or III
4. III

Test Item File Manual, p. 74, item 83

Through which pathway would the least energy be available to humans? (see diagram CH03R011 on page 86 of Test Item File Manual)

1. I
2. I or II
3. II
4. III

Test Item File Manual, p. 75, item 84

In which pathway does the most energy escape as heat? (see diagram CH03R011 on page 86 of Test Item File Manual)

1. I
2. I or II
3. II
4. III

Test Item File Manual, p. 75, item 85

Which pathway will be favored more if the world human population doubles in size? (see diagram CH03R011 on page 86 of Test Item File Manual)

1. I
2. II
3. II or III
4. III

Test Item File Manual, p. 75, item 86

The test bank provides one item to assess the ideas that “Plants break down the sugar molecules that they have synthesized into carbon dioxide and water” (part of Idea b₁) and “Plants get energy to grow and function [from] the sugar molecules” (part of Idea b₂):

What accounts for the fact that gross primary productivity is greater than net primary productivity?

1. decomposers are not part of a community’s energy pyramid
2. plants use most of their energy for growth and repair
3. a stable community has ten times as many herbivores as carnivores
4. all of these

Test Item File Manual, p. 73, item 80

However, the test bank provides no items to assess the other key ideas. While the Applications provide a couple of questions for other key ideas (see questions listed for the criterion Providing Practice), these questions are insufficient to assess the set of key ideas.

Testing for understanding

Rating = Fair
The material provides a sufficient number of items that meet indicator 1 for one key idea but not for the other key ideas.

Indicator 1: Somewhat met
All the assessment items focus on understanding key ideas. However, all but one of the items focus on 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). These items cannot be answered by rote memorization of terms or phrases. However, only one other item is provided to assess understanding of the other key ideas.

Indicator 2: Not met
All of the items are novel, as are the Applications questions. However, the material does not provide familiar tasks for any of the key ideas.

Using assessment to inform instruction

Rating = Poor
Since the material provides no tasks for this criterion, this report is organized to reflect the overall rating rather than each indicator judgment.

The material does not use embedded assessment as a routine strategy. The introduction to the teacher’s guide does indicate that tests can serve to inform instruction:

Tests can increase student comprehension, and they can help you identify concepts that should be retaught. Students should be aware that “missed ideas” will receive your attention. To reteach such ideas, select alternative ways of presenting them, and/or test with a different format, and give students a second chance to learn.

p. T25

However, no questions are identified throughout the chapters that can be used to diagnose students’ remaining difficulties. Similarly, the material does not assist the teacher in interpreting student responses to the end-of-chapter questions in order to diagnose what learning difficulties remain. And the material does not provide specific suggestions to teachers about how to use the information from the end-of-chapter questions 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. Content background notes usually summarize the student text (e.g., pp. T47–T48, Strategies), state main ideas for each lesson (e.g., p. T35, Concepts; p. 71t, Major Concepts) or briefly elaborate on student text concepts (e.g., pp. 10t, 78t). Overall, the teacher content support is brief and localized.

The material provides some sufficiently detailed answers to questions in the student book to help teachers understand and interpret various student responses (e.g., p. T37, Suggested Answers to Applications, answer 5; p. T48, Suggested Answers to Applications, answers 2–3). However, there are some limitations to the responses provided in the teacher notes, which occasionally are brief and require further explanation (e.g., p. T48, Suggested Answers to Problems, answer 1; p. 19t, Investigation 1.2, Discussion, answer 3). In addition, reference to specific text sections for Concept Review questions may not allow teachers to interpret various student responses (e.g., pp. 11–13t, answers 1–6).

The material provides minimal support in recommending resources for improving the teacher's understanding of key ideas. A reference list without annotations subdivided by chapter is provided within each chapter's teacher notes (e.g., pp. T36–T37 and T48, References). 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. In addition, the Teacher's Resource Book has an annotated reference list of software and media resources organized by chapter (pp. x–xxxiii). The annotations identify topics and sometimes specify scientific concepts that are addressed in the resources.

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. For example, students are sometimes asked to design and conduct their own experiments (e.g., p. 513s, Problems, item 6).

The material provides some suggestions for how to respect and value students' ideas. Introductory teacher notes emphasize respecting students' contributions in class discussions (p. T27). In addition, teacher notes state that multiple student answers should be acceptable for some questions (e.g., p. 18t, Investigation 1.2, Discussion, answer 1; p. T37, Suggested Answers to Problems, answer 1).

The material provides some 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 some tasks that ask students to provide evidence or reasons in their responses (e.g., p. 508st, Discussion, item 4; p. 510st, Discussion, items 7–8).

The material provides some 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. 14–17s). In addition, the material discusses the work of current scientists (p. 15s, Pioneers) and contemporary issues in biology (e.g., p. 85s, Biology Today).

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. T28, Cooperative Learning Strategies) and particular directions for cooperative group activities (e.g., pp. 18–19st, Investigation 1.2; pp. 427–428st, Investigation 16.3).

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. 74s, 427s, 637s), but the number of photographs that include people throughout the material are few.

The material provides some illustrations of the contributions of women and minorities to science and as role models. Most of the contributions of women and minority scientists, however, appear in separate sections entitled Biology Today. Biology Today features provide information about current biology research and the work of particular scientists. For example, one Biology Today feature describes the life and work of a plant ecologist, Joy Zedler. The essay discusses Zedler's research emphasis on salt marsh ecology and her pursuit of science in the face of stereotypical expectations of women.

The material suggests multiple formats for students to express their ideas during instruction and assessment, including cooperative group activities and laboratory investigations (e.g., pp. 506–508s), essay questions (e.g., p. 23s, T37, Applications, item 8; p. 94s, T48, Applications, item 6), visual projects (e.g., p. 513s, Problems, item 9), research projects (e.g., p. 19s, Going Further), and written reports (p. T8, Investigations). However, the material does not usually provide a variety of alternatives for the same task in either instruction or assessment.

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, Student Study Guide, and Teacher's Resource Book provide some additional activities for students. Within each chapter, there are Going Further (e.g., p. 19s) and For Further Investigation (e.g., p. 400st) activities in which students may further study a related interest. The Student Study Guide and the Teacher's Resource Book include supplemental activities and investigations similar in complexity to those in the student text (e.g., TRB, pp. 65–66 and 125–126, Supplementary Investigation 7, Relationships Between a Plant and an Animal).

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. 13–14s). In addition, some tasks (e.g., pp. 18–19st, Investigation 1.2; p. 75t, second teacher note; p. 94s, Applications, item 4) 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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