AAAS Project 2061 Textbook Evaluations

Middle Grades Mathematics | Middle Grades Science | Algebra | High School Biology

Menu

• About the Evaluation
• Project 2061 Analysis Procedure
• Browse the Evaluation Reports
• Background Reading
• Home

Biology: Principles & Explorations. Holt, Rinehart and Winston, 1998

Matter and Energy Transformations: Instructional Analysis

I: Providing a Sense of Purpose

Conveying unit purpose

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The unit and chapter openers do not provide a problem, question, representation (or otherwise identified purpose) for the students. Chapter titles—for example, Energy and Metabolism (p. 74s), Photosynthesis and Cellular Respiration (p. 94s), Ecosystems (p. 336s)—indicate what will be covered in the chapter, but they do not state it explicitly as the purpose. The Chapter Theme conveys the intent of each chapter to the teacher—for example, “In this chapter, students will become acquainted with some of the processes of storing and releasing energy within and among living systems” (p. 74t)—but at no time are teachers instructed to share this intent with students. The Authors’ Rationale also informs the teacher about the intent of the chapter—for example, “Through this chapter, students will see where energy comes from, what it does, and where it goes” (p. 94t); “Students will gain an understanding of ecosystem dynamics by studying energy flow between trophic levels, pyramids of energy, and nutrient cycles” (p. 336t)—but again, teachers are not asked to share that intent with the students.

Indicator 2: Not met
Since there is no clearly stated purpose for the students, the comprehensibility of such a purpose cannot be judged. Even if the titles of chapters were considered to be purposes, they are too broadly stated and they use terms that would be unfamiliar to a student who doesn’t already understand the concepts.

Indicator 3: Not met
Once again, since there is no clearly stated purpose for the students, it is impossible to say if the purpose would be interesting and motivating for them. The colorful pictures at the beginning of each chapter convey no purpose, and the chapter titles are not interesting and motivating.

Indicator 4: Not met
Giving students an opportunity to think about and discuss the problem, question, representation (or otherwise identified purpose) is not a characteristic of the material. The Opening Demonstrations do not address the implied purpose for each chapter. For example, a demonstration in which the teacher is to swing a meter stick back and forth and have students identify potential and kinetic energy (p. 74t) is designed to prepare students for the topics covered in the chapter; but it does not engage the students in a discussion about the implied purpose, “Energy and Metabolism.”

Indicator 5: Not met
All of the lessons in a chapter are related to the chapter title, but chapter titles are not explicitly stated as purposes.

Indicator 6: Not met
Without a stated purpose, there is no purpose to return to at the end of the chapter. Students may be asked to complete an activity designed to help them review the chapter content—for example, they are asked to make concept maps relating photosynthesis and cellular respiration (p. 113s) and describing “the role of organisms in the flow of energy through an ecosystem” (p. 355s)—but these activities are not related to a chapter purpose.

Conveying lesson/activity purpose

Rating = Poor
The material meets one out of the five indicators.

Indicator 1: Met
Three features can help to convey the purpose of readings for students:

• Section titles—such as How Energy Cycles (p. 95s) and How Photosynthesis Works (p. 98s)—inform students about what will be happening in those sections.
• Opening paragraphs either directly state the purpose of the section (“In this section you will learn where organisms get their energy and how this energy moves within an ecosystem” [p. 343s]) or imply it (“Energy may sound like a topic that belongs in a physics course, but it is vital to living things” [p. 75s]).
• Section objectives—such as, “Distinguish between potential and kinetic energy,” “Explain what happens when energy is transformed,” “Describe how energy flows through living systems,” and “Identify what happens in an oxidation-reduction reaction” (p. 75s)—are intended to help convey the purpose to the student. The material for teachers at the beginning of the book indicates that section objectives are to “focus students on the section’s most important content” (p. 48T).

Indicator 2: Not met
Both section titles and Section Objectives include technical vocabulary such as “photosynthesis,” “potential” and “kinetic” energy, and “oxidation-reduction reaction” that may not be comprehensible to students who have not already studied the topic.

Indicator 3: Not met
Students are not asked to think about section titles, opening paragraphs, or Section Objectives. Opening Questions—such as “Ask students what relationship the products of photosynthesis have with cellular respiration” (p. 107t); “Ask what advantage a cycle provides for living systems” (p. 349t)—are intended to “[ask] a question about material that has been covered previously” (p. 44T) rather than to have students think about the purpose of the upcoming section.

Indicator 4: Not met
This is not a feature of this material since the material does not convey or prompt the teacher to convey how the material is tied to the unit purpose. Connections, a feature of the teacher notes, “discusses the ways in which a lesson topic relates to material the students have already learned in a previous chapter” (p. 47T); but these ways are neither related to the upcoming section nor to be conveyed to students.

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 at appropriate points. The Capsule Summary sidebars relate to the Section Objectives but do not serve this purpose:

In every energy transformation, some energy is converted to heat, increasing the disorder and the stability of a system.

p. 77s

Carbon enters the living portion of the carbon cycle through photosynthesis. Organisms release carbon through cellular respiration. Carbon long trapped in rock and fossil fuels is freed by erosion and burning, respectively.

p. 352s

Justifying lesson/activity sequence

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

Indicator 1: Somewhat met
In its treatment of this topic, the text moves from presenting transformation of matter and energy at the cellular level (unit 1) to the ecosystem level (unit 4) to the organism level in plants (unit 6) to the organism level in humans (unit 9). Given that students are most familiar with the human organism, the sequence of units makes little sense.

Sometimes the sequence of subsections within a chapter seems logical. For instance, a section on energy flow in the Ecosystems chapter moves from giving steps in the path to describing energy transfer at each step to describing energy loss at each transfer:

16-2 Energy Flows Through Ecosystems

The Path of Energy: Who Eats Whom in Ecosystems

Energy Transfers Between Trophic Levels Are Inefficient

Energy Loss Limits the Number of Trophic Levels in an Ecosystem

pp. 343–348s

Similarly, a section in the chapter on energy and metabolism moves from describing forms to describing changes from one form to another to the inevitable loss during each transformation, and so forth:

4-1 Energy and Living Things

Energy Takes Many Forms

Energy Can Be Transformed

Energy Tends to Become Disorganized

Energy Flows Through Living Systems

Energy Is Carried by Electrons

pp. 75–79s

However, the sequence in other sections makes little sense. For example, the section on photosynthesis moves from where the process occurs to a discussion of light and photosynthetic pigments before discussing what needs to occur:

5-2 How Photosynthesis Works

Plants Are Specialized for Photosynthesis

Light Energy Is Packaged in Photons

Photosynthetic Pigments Absorb Photons

Light Energy Is Converted Into Chemical Energy

Chemical Energy Is Stored in Organic Molecules

Environment Affects the Rate of Photosynthesis

pp. 98–106s

Hence, students are unprepared to appreciate why the leaf is a “wonderfully complex and sophisticated photosynthetic machine” (p. 99s).

Indicator 2: Not met
The material does not convey a rationale for the sequence of units or chapters or for the sequence of readings or other activities within chapters. Although each chapter begins with an Authors’ Rationale, this feature does not provide the logic for the sequence of topics or activities within the chapter. For example, the Authors’ Rationale for Chapter 5: Photosynthesis and Cellular Respiration provides information on what students will study but not why:

The discussion of energy continues here. Energy is stored in the chemical bonds of organic molecules when they are formed and released when these chemical bonds are rearranged. Essentially, the energy-storing bonds are formed during photosynthesis, and then their energy is released during the complementary process of cellular respiration. Through this chapter, students will see where energy comes from, what it does, and where it goes. Energy is examined as it is supplied by the sun, as it is trapped by photosynthesis, as it dwindles through a food chain, and as it is ultimately lost as heat.

p. 94t

Even when a purpose is provided for the information in the chapter, it is cast in vague terms and provides no rationale for the sequence of sections:

Recognizing that species are continually interacting with other species and their nonliving environment is critical to understanding ecology. Ecosystem dynamics are addressed in this chapter, showing your students the interdependence of organisms and how changing one component in an ecosystem, or upsetting the “balance of nature,” can have disastrous results. Students will gain an understanding of ecosystem dynamics by studying energy flow between trophic levels, pyramids of energy, and nutrient cycles.

p. 336t

No other features in this material provide such information to the teacher.

[Top of Page]

II: Taking Account of Student Ideas

Attending to prerequisite knowledge and skills

Rating = Poor
The material fully meets no indicators, but indicator 4 is somewhat met.

Indicator 1: Not met
The material does not alert the teacher to specific prerequisite ideas or skills. While the teacher’s guide notes that the Review feature “identifies topics from earlier chapters that students should understand before beginning the new chapter” (p. 22T), this feature lists only topics, not specific ideas. For example, Chapter 5: Photosynthesis and Cellular Respiration begins with this list:

• proton pumps and chemiosmosis (Section 3-2)
• autotrophs and heterotrophs (Section 4-1)
• laws of thermodynamics (Section 4-1)
• oxidation-reduction reactions (Section 4-1)
• coenzymes and coupled reactions (Section 4-3)

p. 94s

Also, there is no additional information about how the topics on this list relate to any specific ideas taught in the chapter.

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

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

Indicator 4: Somewhat met
The material does not adequately address prerequisites in the same unit or in earlier units. The material presents several prerequisite ideas from physical science in Chapter 4: Energy and Metabolism. The text states the ideas that “Arrangements of atoms have chemical energy” and that “Energy can...change from one form into another” in its introduction to energy transformation (p. 76s). And it mentions the idea that “Different amounts of energy are associated with different...molecules” in its presentation of energy and chemical reactions (p. 81s). However, in both cases these prerequisite ideas are presented alongside much more sophisticated ideas like the first and second laws of thermodynamics (pp. 76–77s) or free energy, activation energy, and endergonic and exergonic reactions (p. 81s).

Even when the presentation of prerequisite ideas is not intruded upon by more advanced material, the prerequisite ideas are mentioned but not discussed. For example, the “fuel” part (but not the “building materials” part) of the prerequisite idea that “Food provides the molecules that serve as fuel and building materials for all organisms” is just mentioned in the introduction to how energy cycles:

Like a rechargeable battery, your body eventually runs low on energy and needs to be supplied with more. You get this energy from food. The energy in your food was first captured from sunlight by photosynthesis. You extract that energy by the process of cellular respiration.

p. 95s

The prerequisite idea that “Carbon and hydrogen are common elements of living matter” is also just mentioned in a teacher introduction to the periodic table (p. 29t). And the idea that when substances interact in a closed system the total mass remains the same, and that the idea of atoms explains this conservation of matter, is not even mentioned.

Indicator 5: Not met
The material makes only one connection between a prerequisite and a key idea. The only connection made is between the idea that energy can change from one form to another and the idea that other organisms get energy to grow and function from food (Idea c₂):

Much of the work done by living things involves energy transformation. When you use food as a source of energy for movement, you are converting chemical energy into mechanical energy. When you use food to help maintain your body temperature, you are converting chemical energy into thermal energy (the random movement of all particles of matter).

p. 76s

But though other prerequisite ideas are stated, they are not connected to the key ideas for which they are prerequisite. For example, the prerequisite idea that “Carbon and hydrogen are common elements of living matter” is not related to the key idea that “Plants make sugar molecules from carbon dioxide (in the air) and water” (Idea a₁). For example, the text does not indicate that the sugars (and molecules derived from them) contain lots of carbon, which is why carbon is such a common element of living matter.

A feature in the teacher’s guide called Connections attempts to link previously covered topics to ideas currently being learned. For example, a Connection in Chapter 5 reads:

Remind students that the materials needed to sustain life ultimately come from the environment. Living systems are efficient recycling factories. The materials (elements and compounds) needed to sustain life cycle through the biosphere in the processes of photosynthesis and cellular respiration.

p. 96t

While the ideas in previous chapters are identified, they are not connected to ideas that are being addressed in the current chapter.

Alerting teachers to commonly held student ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The material does not present specific commonly held ideas that are relevant to the key ideas and have appeared in the scholarly publications. Teachers are not alerted to any of the following commonly held 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 teacher’s guide includes a feature called Overcoming Misconceptions, it typically presents misconceptions not relevant to the key ideas (e.g., “...a food calorie is a measure of energy, not a measure of fat, as is the common misconception” [p.77t]) and/or provides correct content information for the teacher but not information about commonly held student ideas (e.g., “Because ATP supplies most of the energy that drives metabolism, it is sometimes misleadingly called an energy-rich molecule and its phosphate bonds are sometimes misleadingly called high-energy bonds....” [p. 86t], “Glucose is not a direct product of photosynthesis” [p. 105t]). Only one misconception reported in the research literature is noted: “Students often think that because photosynthesis occurs only in autotrophs, cellular respiration occurs only in heterotrophs” (p. 95t; a similar note appears on page 343t).

Indicator 2: Not met
Even the one commonly held idea that is noted is not adequately explained.

Assisting teachers in identifying their students’ ideas

Rating = Poor
The material provides very few questions to help teachers identify students’ ideas. Two indicators are somewhat (but not fully) met.

Indicator 1: Somewhat met
The material includes two features that provide a few questions that could be used by the teacher to find out what students know before instruction begins. The Tapping Prior Knowledge feature includes the following relevant questions:

What is the major source of energy for all cells?
What are some uses of energy within the cell?

p. 74t

What is an ecosystem?
What crucial role do photosynthetic organisms play in most ecosystems?

p. 336t

Where does the energy stored in plants come from?

p. 590t

And the Opening Question (or Opening Demonstration) feature includes the following relevant questions:

...[A]sk students what raw materials living things need to sustain life.

p. 94t

Ask students why energy is necessary to living systems.

p. 95t

Ask students how sunlight is important to living systems.

p. 98t

Ask students to explain how the first and second laws of thermodynamics are involved when a person eats a piece of beef from a cow that has grazed on grass.

p. 343t

However, these questions aren’t sufficient to probe for all the misconceptions students commonly have on this topic.

Indicator 2: Somewhat met
The above questions are comprehensible but are insufficient to probe for all the misconceptions students commonly have on this topic.

Indicator 3: Not met
The questions are not identified as serving the purpose of identifying students’ ideas. Questions in the Opening Question feature ask about information that has been covered previously (as indicated on page 44T) and usually have only one right answer given. For example, after directing teachers to ask students “what raw materials living things need to sustain life,” the teacher’s guide provides a correct answer and tells teachers to correct students that simply list “air” (p. 94t). Teachers are told to “[e]mphasize that air is made of several gases” and the teacher’s guide includes the approximate percentages of the types of gases in air.

Admittedly, the teacher’s guide indicates that questions in Tapping Prior Knowledge “[help] you assess how much your students know—and what misconceptions they may have—before you begin teaching” (p. 44T). But the above questions are about the information treated in prior chapters rather than about commonly held misconceptions. Without knowing what those misconceptions are, the statement about assessing misconceptions in this feature is meaningless.

Indicator 4: Not met
Very few of these questions ask students to give explanations and none ask students to make predictions.

Indicator 5: Not met
The material offers no suggestions for how teachers can probe beneath students’ initial responses to questions. For example, the teacher’s guide does not tell the teacher to listen for his/her students’ responses or to avoid correcting their ideas at this time. Without these warnings, it is unlikely that the questions provided will be used to elicit student ideas. And no suggestions are given that might help teachers interpret student responses in light of the published misconceptions.

Addressing commonly held ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
Although the teacher’s guide includes a feature called Overcoming Misconceptions, it typically presents misconceptions unrelated to the key ideas. Even in the one instance where a reported misconception is listed (as noted above under Alerting Teachers to Commonly Held Student Ideas, indicator 1), the teacher is simply instructed to provide the correct answer: “Emphasize that cellular respiration occurs in all organisms, from the simplest bacteria to the most complex animals and plants” (p. 95t).

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.

[Top of Page]

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. While a total of five phenomena were sighted that could be used to make key ideas credible, only one was explicitly linked to a key idea. For example, two phenomena were included that could, potentially, support the idea that “Plants transfer the energy from light to make ‘energy- rich’ sugar molecules” (Idea a₂), but neither was used to do so. In Chapter 5: Photosynthesis and Cellular Respiration, the text includes a diagram showing both the action spectrum of photosynthesis and the absorption spectra for photosynthetic pigments (p. 101s). Had either the figure legend or accompanying text indicated that the strong correlation of the action and absorption spectra suggests (a) that these pigments are responsible for photosynthesis and (b) that plants actually use light in the process (rather than just needing it), the diagram could have provided support for the part of the idea that says plants use energy from light. And if the action spectrum experiment had been adequately related to the data used to generate it (e.g., peaks indicate wavelengths of light where O₂ production, and hence sugar production, is greatest) it could have provided support for the complete idea. However, neither the figure legend, accompanying text, nor suggested discussion notes for the teacher (p. 101t) do so. The same chapter includes a demonstration, How Light Intensity Affects Photosynthetic Rate (p. 106t). Students are to observe that Elodea produces bubbles in the presence of light but not in its absence. However, none of the discussion questions focus students’ attention on a plant’s use of light:

What did you predict would happen? (Answers will vary.)
What do you think would happen if the heat became too great in the apparatus? (The rate of photosynthesis would decrease.)
Why? (Plant enzymes would be damaged.)

p. 106t

Similarly, two phenomena were included that could have been used to support 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), but they were not used to do so. Chapter 5: Photosynthesis and Cellular Respiration includes a demonstration, Recycling in a Terrarium (p. 95t). One of the questions (“Why put both a plant and an animal in the terrarium?”) could launch a discussion about the combination and recombination of elements in the terrarium and in ecosystems more generally. But the suggested answer (“They recycle raw materials for each other”) does not move the discussion toward considering the combination and recombination of elements (p. 95t). Chapter 16: Ecosystems includes the Laboratory Investigation: Ecosystem in a Jar, in which students are to “Observe the interaction of organisms in a closed ecosystem, and compare this ecosystem with others observed in nature” (p. 358s). But neither the Inquiry nor Analysis questions focus on any key ideas.

One phenomenon, described in the text, is used to support 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....” (Idea d₂). The text notes that “a large human population could not survive by eating lions captured on the Serengeti Plain of Africa” (p. 347s) and then goes on to explain that the loss of energy at each trophic level means the number of lions that can survive (from eating the number of zebras that can live on the available grass) is insufficient to feed a large population of humans.

The Laboratory Investigation: Chromatography of Plant Pigments, a mainstay of biology textbooks, does not address any key ideas (pp. 116–117s).

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 one phenomenon was provided, there is essentially nothing to be judged for vividness.

[Top of Page]

IV: Developing and Using Scientific Ideas

Introducing terms meaningfully

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The material does not link new technical terms to relevant experiences. With few relevant phenomena, there seems to be little point to using the terms other than to have students learn their definitions. For example, terms like “open” and “closed” system (p. 76s), “photosynthesis” (p. 77s), “enzymes” (p. 82s), and “ecosystem” (p. 338s) are defined in the abstract with no helpful examples given to make the terms concrete for students. Even when the terms are linked to a representation, the representation is often incomprehensible and hence does not provide a helpful concrete experience to make the terms meaningful to students. For example, see the energy flow diagram (p. 78s), reaction progress diagrams (p. 81s), and overview of photosynthesis diagram (p. 98s). Some representations include additional new terms (e.g., “nitrogen cycle” on page 353s), making it even less likely that they will help to clarify the new terms needed to communicate about the key ideas.

Indicator 2: Not met
The material does not restrict the use of technical terms to those needed to communicate intelligibly about the benchmark ideas. For the key ideas for flow of energy and transformation of matter, unnecessarily introduced terms include: “thylakoid,” “granum,” “stroma,” “radiant energy,” “electromagnetic spectrum,” “photon,” “pigment,” “chlorophyll,” “coenzyme,” “allosteric site,” “carotenoids,” “photosystem,” “photosystem I,” “photosystem II,” “reaction center,” “electron transport chain,” “ATP synthetase,” “reducing power,” “NADPH,” “NADP+,” “carbon fixation,” and “Calvin cycle.”

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 has hardly any representations that are accurate, comprehensible, and explicitly linked to the real thing being represented. So little support is provided to clarify the key ideas for students.

Out of the nearly twenty representations examined, only one satisfies all three indicators: To clarify 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...” (Idea d₂), the text uses a diagram to represent the energy loss at each trophic level in an aquatic ecosystem (p. 347s). The figure legend both explains the figure and points out its limitations:

This simple aquatic ecosystem contains four trophic levels. Each trophic level contains about 90 percent less energy than the level below it. Because of space considerations, the trophic levels are not shown to scale here.

p. 347s

The figure uses pictures (rather than just the terms) for producers, herbivores, carnivores, and top carnivore) to clarify the kinds of organisms at each trophic level, and another part of the figure represents those same organisms as they might be found in nature. The accompanying text provides a real-life example to make the link to the real thing:

Most terrestrial ecosystems involve only three or, rarely, four levels. Too much energy is lost at each level to allow more levels. For example, a large human population could not survive by eating lions captured on the Serengeti Plain of Africa; there are simply too few lions to make this possible. The amount of grass in that ecosystem cannot support enough zebras to maintain a large enough population of lions to feed lion-eating humans. The ecological complexity of the world is thus fixed in a fundamental way by the loss of potential energy that occurs at each trophic level. This loss is a consequence of the second law of thermodynamics, which you studied in Chapter 4.

p. 347s

Unfortunately, other representations are not likely to help clarify key ideas for students. Most representations are not accurate, comprehensible, or linked to the real thing. For example, the figure representing a cycle between chloroplasts and mitochondria does not accurately represent either matter or energy transformation; if matter transformations are being represented, then it (erroneously) shows ATP appearing out of nowhere (rather than out of ADP + P). On the other hand, if it is supposed to be representing energy transformations, then it shows only sunlight and heat (rather than also indicating that glucose is “energy-rich”). The numerous diagrams of metabolic pathways (e.g., pp. 98s, 102s, 103s, 105s, 107s, 108s, 109s) are not likely to be comprehensible without considerable text explanation. Even so, they are needlessly complex for clarifying the key ideas. Even the seemingly simple equations can cause problems. For example, equations for photosynthesis (p. 98s) and cellular respiration (p. 107s) represent carbohydrates as CH₂O, even though the formula for carbohydrates was previously given as (CH₂O)_n (p. 34s).

Even the analogies suggested to the teacher are not likely to be helpful. For example, the analogy for electrons and energy involving bowling balls and where people live in a building (p. 77t) is so confusing that between bowling balls, the residents’ pay, and what floor they live on, it is hard to imagine how students could ever get the key idea out of it. It is inaccurate (e.g., What does the pay of the people have to do with their bowling balls?), too confusing to be comprehensible, and not linked to the idea.

Similarly, the demonstration on burning and comparing it to cellular respiration (p. 107t) is likely to be incomprehensible. When the students are asked “What are the reactants of this reaction?,” the expected answer is “alcohol, which is an organic compound, and oxygen.” Most students would say the wick is burning and few would know that alcohol is organic. If the point is to burn something as a comparison to respiration, why not use a food source, such as marshmallows, which students could eat while observing the burning? Both would yield the same products (and this analogy could provide a better frame to establish the purpose of the lesson).

Demonstrating use of knowledge

Rating = Poor

The material meets no indicators.

Indicator 1: Not met
The material does not consistently demonstrate the use of key ideas or suggest how teachers could do so. In only one instance does the material demonstrate the use of a key idea: The text uses 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....” (Idea d₂) to explain why most terrestrial ecosystems involve only three or four trophic levels:

Most terrestrial ecosystems involve only three or, rarely, four levels. Too much energy is lost at each level to allow more levels. For example, a large human population could not survive by eating lions captured on the Serengeti Plain of Africa; there are simply too few lions to make this possible. The amount of grass in that ecosystem cannot support enough zebras to maintain a large enough population of lions to feed lion-eating humans. The ecological complexity of the world is thus fixed in a fundamental way by the loss of potential energy that occurs at each trophic level. This loss is a consequence of the second law of thermodynamics, which you studied in Chapter 4.

p. 347s

Indicator 2: Not met
The demonstration begins nicely, providing a step-by-step explanation of why the Serengeti Plain could not support a large human population. But then it needlessly falls back on technical terms such as “potential energy” and “the second law of thermodynamics.” One instance does not merit credit for this indicator.

Indicator 3: Not met
The single instance of demonstrating the use of a key idea to explain a phenomenon is not identified as a demonstration.

Indicator 4: Not met
No running commentary that points to particular aspects of the demonstration is provided; nor does the material provide criteria for judging the quality of a performance.

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.

Two kinds of questions and tasks were considered for this criterion. These included Chapter Review questions and student tasks and questions within the chapter requiring application of ideas presented in the text. The material provides some tasks, including novel tasks, for some key ideas but not for others.

The material provides tasks, including novel 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) and 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....” (Idea d₂). For example, the following questions were considered to be novel:

Question: A scientist measuring atmospheric carbon dioxide levels in a Michigan deciduous forest (deciduous trees, such as elms and maples, shed their leaves in the fall) finds that the carbon dioxide levels fluctuate during the year, as shown in the graph below. Using your knowledge of the carbon cycle, explain the cause of these fluctuations.

Suggested Response: Carbon dioxide levels fall in the spring, when new plant growth is removing large amounts of carbon dioxide from the atmosphere. In the fall, plants die and trees lose their leaves. Carbon dioxide levels rise because of the decomposition of leaves and other plant parts and because photosynthesis stops due to low temperatures.

pp. 357s and 356t, question 26

Question: Energy flow in an ecosystem is described in terms of the activities of producers, consumers, and decomposers. What is the role of each of these in the carbon cycle?

Suggested Response: Producers, such as plants, use carbon dioxide to build carbohydrates. They also release carbon dioxide when carbohydrates are broken apart during respiration. Consumers take in carbon as carbohydrates when they eat foods and use the carbohydrates to build their own bodies. Like producers, consumers release carbon to the air as carbon dioxide during respiration....

pp. 357s and 356–357t, question 28

Question: For every 100 units of energy available from alfalfa, cattle that eat the alfalfa capture only 10 units of that energy, and humans that eat the cattle as hamburger capture only 1 unit of that same energy. How do you account for this inefficient transfer of energy?

Suggested Response: As the second law of thermodynamics indicates, there is not a perfect exchange of energy between living systems. When energy is transferred from one organism to another, some energy is lost as heat.

p. 91st, question 34

Question: Reptiles, such as the Komodo dragon shown below require about one-tenth as much food as mammals, which have much faster metabolic rates. On the Serengeti Plain of Africa, the ratio of lions to their prey is about 1 to 1,000. If Komodo dragons instead of lions were the top predators on the Serengeti Plain, would the ratio of predators to prey be higher, lower, or the same? Explain your answer.

Suggested Response: Because one Komodo dragon requires less energy than one lion, the Serengeti Plain could support more Komodo dragons than lions and the predator-to-prey ratio would be higher.

p. 356st, question 23

Other questions were not considered novel, because the answer can be copied from the text:

Question: Nutrients can be reused, but energy cannot. Explain why.

Suggested Response: Nutrients can be recycled because they are not converted into an unusable form. Even the wastes of organisms contain materials that are needed by other organisms. When an energy transfer occurs in an ecosystem, however, some energy is always “lost” as heat. Heat cannot be recaptured for use.

p. 354s, question 4; p. 354t:
The information is presented in the opening paragraph on page 349s

Question: Food chains usually consist of no more than three or four trophic levels. Explain why.

Suggested Response: Because so little of the energy stored by the organisms at one trophic level is transferred to organisms at the level above. As a result, there is not enough energy at the highest level to support an additional level.

p. 356s, question 19; p. 356t:
The information is presented on page 347s

For other key ideas, only one question is provided. For example, the following question is the only one found that gives students a chance to practice using the idea that “Plants transfer the energy from light to make ‘energy-rich’ molecules” (Idea a₂) and the idea 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):

Question: Describe the flow of energy that results in your being able to obtain energy for metabolism by eating a T-bone steak.

Suggested Response: Light energy from the sun is converted to chemical energy in grass by the process of photosynthesis. The grass is eaten by a cow that uses the energy available in the grass to build body tissue. Steak that comes from the cow is eaten by humans and provides them with energy.

p. 90st, question 30

And no questions or tasks are provided for students to practice using the idea that “Plants get energy and function by oxidizing the sugar molecules. Some of the energy is released as heat” (Idea b₂) or 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).

The material does not provide a sequence of questions or tasks in which the complexity is progressively increased.

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

[Top of Page]

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

Encouraging students to explain their ideas

Rating = Poor
The material meets no indicators.

Indicator 1: Not met
The material does not routinely encourage students to express their ideas. Only four questions/tasks were included that appear to be intended for having students express their own ideas. Students are asked to make concept maps of relevant terms (e.g., pp. 89st, 113st, 355st). While a single answer is provided, the teacher’s guide notes that it is only one possibility.

While questions were provided in Teaching Tips (e.g., pp. 81t, 87t, 110t, 111t), Chapter Closure (e.g., p. 88t), and Visual Strategy (e.g., pp. 82t, 87t, 95t, 97t, 342t, 344t, 345t), only one of these examples includes questions specific to the key ideas.

Neither Section Review nor Chapter Review questions, which provide the correct answer, were considered. The focus on the correct answer suggests the questions are not really designed to elicit the students’ ideas.

Indicator 2: Not met
The Chapter Reviews ask students to make concept maps, which do give them a chance to represent their ideas; however, an answer is always provided (e.g., pp. 89st, 113st, 355st). Students are not asked to clarify or justify their concept maps.

Indicator 3: Not met
Since most of the questions do not apply to this criterion, it is not relevant that students are expected to write answers to those questions.

Indicator 4: Not met
The material does not include specific suggestions to help the teacher provide explicit feedback to students nor does the text do so.

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

Guiding student interpretation and reasoning

Rating = Poor
One indicator is somewhat met.

Indicator 1: Somewhat met
The material includes specific questions at the end of each text section and laboratory activity. Each text section includes a Section Review that provides three to four questions about its content. A few of these questions (and answers) are relevant to the key ideas:

Question: What roles do photosynthesis and cellular respiration play in the flow of energy through living systems?

Suggested Response: Photosynthesis traps the energy of sunlight, storing it in sugars. All organisms use the sugars in cellular respiration to meet their energy needs.

p. 79st, question 3

Question: How do plants use the products of photosynthesis?

Suggested Response: Plants use carbohydrates as an energy source to sustain themselves when no sunlight is available and for metabolic activities in their roots and other nonphotosynthetic tissues. They also use carbohydrates as raw materials for making the other carbohydrates, fats, proteins, and nucleic acids they need. Plants use oxygen in cellular respiration.

p. 97st, question 2

Question: Because of the second law of thermodynamics, food chains normally involve no more than three or four organisms. Why do you think this is so?

Suggested Response: Energy is lost at each step of a food chain. Since no new energy can be created by each level, the total amount of usable energy in the system dwindles as it moves through a food chain. Ultimately, not enough energy is available to support another level.

p. 97st, question 4

Question: Suppose you want to create an ecosystem in an aquarium. Explain why your ecosystem would require producers.

Suggested Response: Only producers can capture energy and convert it into a usable form.

p. 348st, question 1

Question: Explain why a given area of land could support more vegetarian humans than omnivorous humans.

Suggested Response: If plants are fed to a herbivore to produce meat, 90 percent of the energy in those plants is lost. Vegetarians skip this energy-losing step, and more energy is available to support more people.

p. 348st, question 3

Question: Nearly all the mammals that humans eat, including cows, sheep, and goats, are herbivores, not carnivores or omnivores. Explain why a herbivore is a more efficient meat producer from an energetic point of view.

Suggested Response: The logic here is the same as that in question 3.

p. 348st, question 6

Most of the above questions involve only recalling information from the text.

While the material includes questions at the end of relevant laboratory investigations and some demonstrations, none of the questions focus on the key ideas. For example, after observing that Elodea produces bubbles in the presence of light but not in its absence, none of the questions focus students’ attention on a plant’s use of light:

What did you predict would happen? (Answers will vary.)
What do you think would happen if the heat became too great in the apparatus? (The rate of photosynthesis would decrease.)
Why? (Plant enzymes would be damaged.)

p. 106t

The same is the case for questions at the end of Demonstration: Recycling in a Terrarium (p. 95t) and those at the end of Laboratory Investigation: Ecosystem in a Jar (p. 359s). Other relevant demonstrations (e.g., Demonstration: Burning an Organic Fuel [p. 107t]) do not include questions.

Teaching Tips, Closure, and Visual Strategy features rarely have questions relevant to the key ideas.

Indicator 2: Not met
None of the questions in the Section Reviews has helpful characteristics such as framing important issues, helping students make connections between their own ideas the presented scientific ideas, or anticipating student misconceptions.

Indicator 3: Not met
None of the Section Reviews involve scaffolded sequences of questions, which could guide students from phenomena or their own ideas about phenomena to scientific ideas. Instead, Section Reviews include only individual questions on a particular idea.

Encouraging students to think about what they have learned

Rating = Poor
The material somewhat meets the first indicator.

Indicator 1: Somewhat met
The material gives students an opportunity to revise their initial ideas based on what they have learned. The teacher’s guide indicates that “Section Reviews help students check their content mastery” (p. 48T) and that “...test[s] should be reviewed by the student and incorrect responses should be corrected by the student before the test becomes part of the portfolio” (p. 49T). However, since students’ ideas are not solicited before instruction and most of the answers to the Section Review questions are included in the preceding text, it is not clear how these questions will encourage students to revise their initial ideas.

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

[Top of Page]

VI: Assessing Progress

To assess students’ understanding of concepts at the end of instruction, Biology: Principles & Explorations provides a test for each chapter and includes a generic Portfolio Assessment suggestion—to have students construct a concept map from each chapter (p. 49T). These options in chapters 4, 5, and 16, the chapters that treat the key ideas of matter and energy transformations most extensively, were examined for the first two criteria.

At the beginning of the teacher’s guide, the developers state that “Chapter Reviews thoroughly evaluate content mastery” (p. 48T). However, in the Block Scheduling Guide that precedes each chapter (e.g., pp. 73A–73B, 93A–93B, 335A–335B), the Chapter Reviews are not listed as assessment options and therefore were not examined for these criteria.

Aligning assessment to goals

Rating = Poor
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.

Biology: Principles & Explorations includes only three questions in tests that assess the key ideas, which is far from sufficient. One question is included that assesses the idea that “Plants transfer the energy from light into ‘energy-rich’ sugar molecules” (Idea a₂): Students are asked to “explain how plants and certain bacteria may obtain energy from their environments and store it for later use” (Chapter Tests, p. 12, question 21). (Suggested Response: “Plants and algae use photosynthesis to convert light energy into chemical energy, creating energy-storing macromolecules....” [Chapter Tests, p. 128, Essay, answer 21].)

Another item addresses the idea that “Plants make sugar molecules from carbon dioxide (in the air) and water” (Idea a₁): “All organic molecules contain carbon atoms that ultimately can be traced back in the food chain to carbon dioxide from the atmosphere” (pp. 13, 128, question 5).

And another item addresses the idea that “At each link in a food web, some energy is... dissipated into the environment as heat” (part of Idea d₂): Students are asked to complete the statement, “Every time energy is transferred in an ecosystem, potential energy is lost as heat” (pp. 47, 132, question 18).

No other items are provided to assess the key ideas about matter and energy transformations.

Testing for understanding

Rating = Poor
Since no assessment tasks were aligned to the key ideas, the report for this criterion is organized to reflect the overall rating rather than each indicator judgment.

Of the relevant assessment items described under the previous criterion, none require understanding of the key ideas. Clearly this is not sufficient to assess students’ understanding of the key ideas examined here.

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.

Biology: Principles & Explorations does not make any claims about assessing students throughout instruction to diagnose their remaining difficulties and modify the instruction accordingly.

[Top of Page]

VII: Enhancing the Science Learning Environment

Providing teacher content support

Rating = Minimal 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 briefly elaborate on one or a few student text concepts (e.g., p. 105t, Teaching Tips: A Source of Energy and Organic Building Materials), briefly explain peripheral information (e.g., p. 111t, Did You Know?), or offer tidbits of questionable relevance (e.g., p. 85t, Did You Know?). Overall, the teacher content support is brief, localized, and fragmented.

The material does not usually provide sufficiently detailed answers to questions in the student book for teachers to understand and interpret various student responses. While most answers include expected scientific responses, little, if any, additional information is provided to help teachers field potential student questions or difficulties (e.g., p. 79t, Answers to Section Review, answer 3; p. 97t, Answers to Section Review, answers 1–2). In addition, some answers are brief and require further explanation (e.g., "Increase aerobic exercise and reduce caloric intake" [p. 112t, Answers to Section Review, answer 6]). Some questions go unanswered (e.g., p. 74t, Tapping Prior Knowledge).

The material provides minimal support in recommending resources for improving the teacher's understanding of key ideas. The material lists resources available within supplemental program materials in introductory notes (pp. 26T–41T) and in the "Program Resource Key" at the beginning of each chapter (e.g., p. 335Bt). 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 = Minimal 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 each Laboratory Investigation, students are asked to write a question that could be studied in another investigation (e.g., p. 359s, Further Inquiry).

The material provides a few suggestions for how to respect and value students' ideas. Introductory teacher notes about concept mapping give criteria for evaluation of maps but also state that "there is not a single correct map for an idea" (p. 51T). In addition, teacher notes state that multiple student answers should be acceptable for some questions (e.g., p. 359t, Inquiry Answers, answers 1–3).

The material provides a few 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?" However, it does not encourage students to pose such questions themselves. Specifically, the material includes a few tasks that ask students to provide evidence or reasons in their responses (e.g., p. 95t, Demonstration; p. 359s, Analysis, items 1–2).

The material provides a few suggestions for how to avoid dogmatism. The first chapter portrays the nature of science as a durable yet dynamic human enterprise in which all people can participate (e.g., pp. 5–7s, 15–18s). The material also describes developments in scientific thinking about photosynthesis (p. 104t, Historical Note) and discusses related current issues in biology (e.g., p. 79t, Research Update). In each Chapter Review, students are asked to read and respond to popular science articles (e.g., p. 115s, Readings, item 34). However, the material also contributes to dogmatism by presenting most of the text in a static, authoritative manner with little reference to the work of particular, practicing scientists and expecting single, specific responses for most student tasks.

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, a limited sense of desirable student-student interactions may be gained from procedural directions for laboratory and cooperative group activities (e.g., p. 358st, Laboratory Investigation; p. 357s, Activities and Projects, item 30).

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 and illustrations include a diverse cultural mix of students and adults (e.g., pp. 348s, 875s, 886s), 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 Multicultural Perspectives and Historical Notes. Multicultural Perspectives provide information about particular cultural groups related to the chapter content (e.g., p. 338t). Historical Notes sometimes describe the contributions of specific scientists, some of whom are women and minorities. For example, one Historical Note describes the isolation of the enzyme diastase and adrenaline by the Japanese scientist, Jokichi Takamine (p. 87t). In most Chapter Reviews, a question labeled "Multicultural Perspective" asks students to investigate a particular group's cultural contributions, which are related to chapter material (e.g., p. 115s, Activities and Projects, item 32). All of these sections highlighting cultural contributions are interesting and informative, but some may not be seen by students as central to the material because they are presented in sidebars and teacher notes.

The material suggests multiple formats for students to express their ideas during instruction and assessment, including cooperative group activities (e.g., p. 115s, Activities and Projects, items 30–31), laboratory investigations (e.g., p. 358s), whole class discussions (e.g., p. 80t, Opening Questions), essay questions (e.g., p. 356t, 357st, Critical Thinking, item 28; Chapter Tests, p. 12, item 21), concept mapping (p. 355s), research projects (e.g., p. 357s, Activities and Projects, item 29), and portfolio (e.g., p. 112t, Chapter Closure). 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, supplemental program resources provide additional activities and resources for students (for a description, see pp. 38T–39T).

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., p. 75s). In addition, some tasks—including Opening Questions (e.g., p. 337t) and some Chapter Review questions (e.g., p. 90s, Themes Review, item 30)—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, support is brief and localized.

[Top of Page]