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Middle Grades Science Textbooks: A Benchmarks-Based Evaluation

Science Interactions. Glencoe/McGraw-Hill, 1998
Earth Science Life Science Physical Science

About this Evaluation Report
Content Analysis
Instructional Analysis
[Explanation] This section examines whether the curriculum material's content aligns with the specific key ideas that have been selected for use in the analysis.
[Explanation] This section examines whether the curriculum material develops an evidence-based argument for the key ideas, including whether the case presented is valid, comprehensible, and convincing.
[Explanation] This section examines whether the curriculum material makes connections (1) among the key ideas, (2) between the key ideas and their prerequisites, and (3) between the key ideas and other, related ideas.
[Explanation] This section notes whether the curriculum material presents any information that is more advanced than the set of key ideas, looking particularly at whether the “beyond literacy” information interrupts the presentation of the grade-appropriate information.
[Explanation] This section notes whether the curriculum material presents any information that contains errors, misleading statements, or statements that may reinforce commonly held student misconceptions.


Idea a: Food (for example, sugars) provides molecules that serve as fuel and building material for all organisms.
There is a content match, mostly at the level of substances (rather than molecules). More than 20 instances were noted that relate to this key idea, mainly in course 3. The chapter in course 3 on organic chemistry (chapter 10) describes the molecular composition of carbohydrates, proteins, and lipids, and indicates that proteins serve as building material, whereas carbohydrates and lipids are energy stores. However, subsequent chapters treat the idea that food is building material in terms of substances, rather than molecules. Course 3, Chapter 11: Fueling the Body states the idea explicitly (pp. 339t, 352t, 361s) and describes the uses of food for energy (pp. 346–347s), for providing building materials “to effectively repair wounds, such as scrapes, cuts, or broken bones,” and for growth and development (p. 350s). Examples of food serving as energy or building materials are given (in cows, birds, humans, elephants, and lions). Course 2 includes a demonstration of a peanut burning to show that food can serve as a source of stored energy (Chapter 19: How Cells Do Their Jobs, p. 613s).

Idea b: Plants make their own food, whereas animals obtain food by eating other organisms.

There is a content match. The most extensive treatment is in course 1, Chapter 9: Animal Life, which states clearly the distinction between plants and animals:
[A]nimals can’t make their own food. Green plants, on the other hand are producers. Producers make their own food…. In contrast to plants, animals are consumers. Consumers are organisms that are unable to make their own food. They must consume other organisms in order to obtain energy. [p. 280s]

The text then describes various animal adaptations for obtaining the food required (pp. 280–281s). Course 1, Chapter 10: Plant Life introduces photosynthesis with a similar statement of the distinction between producers and consumers (p. 336s), as does course 1, Chapter 11: Ecology in characterizing organisms in their environments (p. 352s).

The idea is treated in the text (see above), in an activity in which students classify organisms on their ability to make or not make food (p. 352st), and in questions in each chapter that check students’ understanding of the distinction (p. 308st, Understanding Ideas, item 1; p. 309st, Connecting Ideas, item 3; p. 315st, Check Your Understanding, item 1).

Idea c: Matter is transformed in living systems.

Idea c1: Plants make sugars from carbon dioxide (in the air) and water.

There is a content match. The idea is introduced in course 1, chapter 10 in the description of plant processes (p. 336s), given as an example of a chemical reaction that absorbs energy (course 2, chapter 18, p. 566), and assessed a couple of times (e.g., students are asked to compare photosynthesis and respiration in course 2, chapter 19, p. 602s). In course 1, chapter 10, the text states the idea and then describes what happens to the products. The equation is not used, but, instead, the names of the starting and ending products of photosynthesis (and respiration) are represented in a drawing that includes the sun, a carrot, and a rabbit (p. 336s). This drawing is repeated in the review of the main ideas in the chapter (p. 341s).

Idea c2: Plants break down the sugars they have synthesized back into simpler substances—carbon dioxide and water—and assemble sugars into the plants' body structures, including some energy stores.
There is a partial content match. The following presentation of Idea c2 shows which parts of the idea are treated (in bold) and what alternative vocabulary, if any, is used (in brackets): Plants [Cells] break down the sugars they have synthesized back into simpler substances—carbon dioxide and water—and assemble sugars into the plants’ body structures, including some energy stores. Course 1 states a less sophisticated version of this idea in the context of describing plant processes:
Let’s look at what happens to the products formed during photosynthesis. Some of the sugars formed are used by the plant for its own life processes, such as growth. Some sugar is stored. When you eat carrots or potatoes, you are eating stored food. [Chapter 10: Plant Life, p. 336s]

Students are expected to repeat this statement in responding to questions (e.g., p. 336st, Check your Understanding, item 2).

Course 2 presents components of this idea in the account of cellular respiration (chapter 19, p. 595st) but does not tie them together. Alongside a diagram of a mitochondrion in a human cell (p. 595st, Figure 19–8), the inputs and outputs of cellular respiration are shown. Adjacent text describes the process of respiration in humans and then implies that plants also respire; but the focus is on energy transformation:

But what about plants? Plants don’t feel warm. Do plants carry out respiration? In the following activity, you can prove to yourself that plants carry out respiration, and that this process converts one form of energy to another. [p. 595s]

Two pages later, the text notes that cells respire, and it gives the waste products of respiration but does not make the connection to plants:

Cells, like most factories, produce waste. The waste products of respiration are water and carbon dioxide. They are released from your body when you are exhaling. Nearly all organisms give off carbon dioxide as a result of respiration. [p. 597s]

Idea c3: Other organisms break down the stored sugars or the body structures of the plants they eat (or in the animals they eat) into simpler substances and reassemble them into their own body structures, including some energy stores.

There is a partial content match. The following presentation of Idea c3 shows which parts of the idea are treated (in bold) and what alternative vocabulary, if any, is used (in brackets): Other organisms break down the stored sugars or the body structures of the plants they eat (or in the animals they eat) into simpler substances and reassemble them into their own body structures, including some energy stores.

The idea that animals break down their food is mentioned in course 1 (chapter 9, p. 284s), mentioned again in course 2 in the context of cellular respiration (chapter 19, p. 595s), and described in some detail in course 3 in the section on human digestion (chapter 11, pp. 351–360s). Students observe the conversion of starch to sugar by an enzyme in their mouths. The further breakdown of glucose to carbon dioxide and water is used to demonstrate the conservation of atoms in course 2, chapter 19 (pp. 600–601s). The idea that organisms break down food and the pieces reassemble into their own body structures is mentioned briefly in the explanation of human digestion:

Digestion is a disassembly line where foods you eat are taken apart. Digestion is the process that breaks down carbohydrates, fats, and proteins into smaller and simpler molecules that can be absorbed and used by the cells in your body. Later, your cells use these molecules as building blocks for growth and repair and as fuel from which energy is released. [course 3, chapter 11, p. 351s]

There is not a content match to the part of this key idea that some of the digested food is reassembled into some energy stores. While chapter 11 presents information on nutrition in the context of a balanced diet, it does not deal with situations of unbalanced input and output. (If input exceeds use, the excess would be stored as fat.)

Idea c4: Decomposers transform dead organisms into simpler substances, which other organisms can reuse.

There is a content match. The idea is stated explicitly several times in course 1—while describing the role of bacteria and fungi as recyclers (Chapter 8: Viruses and Simple Organisms, pp. 257s, 265s) and later in describing the role of decomposers in ecosystems (chapter 11, p. 353s). Although the text includes photographs of decomposers—for example, mold or fungus on a log, a compost pile—it does not show the actual phenomenon that could be explained by the action of decomposers—for instance, the rotting of a log or the “loss” of matter in a compost pile over time (and the subsequent usefulness of the resulting material as fertilizer).

Idea d: Energy is transformed in living systems.

Idea d1: Plants use the energy from light to make "energy-rich" sugars.

There is a content match. The idea appears mainly in text; it is introduced in the context of photosynthesis (course 1, chapter 10) and ecosystems (course 1, chapter 11), presented as an example of a reaction that uses energy (course 2, Chapter 18: Chemical Reactions), and then portrayed as a part of the story of cells and energy (course 2, chapter 19). In course 1, a simpler version of this key idea is given—that plants use light energy to make food. After using the reaction as an example of an endothermic reaction, the more sophisticated version of the idea is presented:
Green plants convert light energy from the sun into sugars through the process of photosynthesis. The sugar produced contains a form of chemical energy. This same chemical energy is passed on to you through the food chain. [course 2, p. 594s]

Idea d2: Plants get energy by breaking down the sugars, releasing some of the energy as heat.

There is a content match. The idea is treated mainly in course 2, in the context of cellular respiration (chapter 19). Although most of the text centers on respiration in human cells, a paragraph implies that plants respire and students then observe that soaked seeds give off heat, whereas unsoaked seeds do not. The text sums up and explains the finding:
You saw evidence that the soaked beans released energy by respiration. You were able to measure the release of stored energy in the soaked beans by comparing the temperatures of the two treatments. Cells use the energy released by respiration in a variety of ways. Nerve cells need energy to transmit messages through the body. Plant cells need energy to form beautiful and complex flowers. [p. 596s]

Idea d3: Other organisms get energy to grow and function by breaking down the consumed body structures to sugars and then breaking down the sugars, releasing some of the energy into the environment as heat.

There is a content match. The idea is treated in several contexts, mainly in course 2. In the description of cellular respiration, the idea that respiration releases energy is stated (Chapter 16: Breathing, p. 497s; Chapter 17: Basic Units of Life, p. 531s). In the account of exothermic reactions, several phenomena are used. First, students are reminded that they feel warm when they have a fever because chemical reactions that release energy are occurring (chapter 18, p. 564t). The text then describes the role of sugar and starch as fuel to provide the energy needed for running at peak performance:
When you eat foods with sugar, such as refined white sugar, your body can quickly use the sugar as fuel to provide needed energy. Inside your body’s cells, the sugar combines with oxygen. This chemical reaction, called respiration, provides quick energy.... The starches in carbohydrates cannot provide quick energy because they are composed of several joined sugar molecules. There must be a chemical reaction to break apart the starch molecule. Then, the resulting sugar can be used by the cell for energy. [pp. 564–565s]

Subsequently, students observe an activated hot pack and feel the warmth generated (p. 565t). The idea is presented again in the description of cellular respiration in the next chapter:

Organisms that depend on oxygen carry out respiration. Your brain cells, kidney cells, skin cells, and the cells in your big toe are using energy released during respiration. So are the leaves on the trees in the local park.
How can you tell if your body cells are producing energy? Feel your own forehead. It feels warm, doesn’t it? What you are feeling is the heat energy produced as a product of the thousands of respiration reactions occurring in your body. [course 2, chapter 19, p. 595s]

Idea e: Matter and energy are transferred from one organism to another repeatedly and between organisms and their physical environment.

There is a content match. However, the main emphasis is on the transfer of energy in food chains. The idea that energy is transferred from one organism to another in food chains is described in the text in course 1 (chapter 11, p. 356s) and listed as a main idea in the chapter review (p. 374s). It is revisited in course 2 in introducing cells and energy (chapter 19, p. 594s). The account of the transfer of matter is less direct. Although it is listed as a main idea in the review of the ecology chapter (“Many materials, such as water, oxygen, carbon dioxide, and nitrogen, are constantly being recycled through the environment” [course 1, chapter 11, p. 374s]), it is not treated in the text, illustrations, or activities. At the end of the unit, students are asked to apply the idea that matter is transferred between organisms and their physical environment by tracing the pathway of water from soil, through a vascular plant to its leaves, and back again to the soil, and to explain what processes occurred and where (p. 337s). However, this idea is never treated explicitly in the unit.

Building a Case

The text asserts the key life science ideas without developing an evidence-based argument to support them. Further, it does not provide examples of phenomena that could be explained by these ideas. For example, the heat generated by a compost pile (or fermenting grape juice) could be used to make plausible the idea that living things release heat while breaking down their food (Idea d3). Although activities involving growing yeast and compost piles are mentioned, neither is offered as evidence to support any idea, nor is evidence offered for the assertion that plants use carbon dioxide and water to make sugars (Idea c1).


This set of key life science ideas tells a story of matter and energy transfer and transformation that spans several levels of biologic organization—ecosystems, organisms, cells, and possibly molecules. Links between the life and physical sciences are particularly important, as, for example, in linking the transformation of matter and energy in physical systems (where it may be easier to keep track of the beginning and ending products of matter and energy).

Science Interactions is an integrated program in that it distributes the Earth, life, and physical sciences over three grades (rather than including the content of a single discipline in each grade). As stated in the introductory material, “[T]he series helps you teach some of the basic concepts from physical science early on. This, in turn, makes it easier for your students to understand other concepts in life and Earth science” (p. 11T). The program also attempts to make numerous connections among the sciences and between science and technology. This organization has implications for the coherence of the presentation of the key life science ideas.

The table below shows how the key life science ideas are distributed over the three courses. Nearly all of the ideas are treated in multiple chapters and often in multiple courses. This makes it possible for students to encounter these ideas in a variety of contexts. (It should be noted that this table was prepared by the reviewers. The material itself does not alert teachers to how the ideas are distributed.)

Course, Chapter, Chapter Name
Key Life Science Idea
a b c1 c2 c3 c4 d1 d2 d3 e
1.8 Viruses and Simple Organisms
1.9 Animal Life
1.10 Plant Life
1.11 Ecology
2.16 Breathing
2.17 Basic Units of Life
2.18 Chemical Reactions
2.19 How Cells Do Their Jobs
3.10 Organic Chemistry
3.11 Fueling the Body

In the course materials, however, little attempt is made to relate the ideas to one another or to ideas in physical science. For example, no attempt is made to connect energy transformations in cells, organisms, and ecosystems. The idea that energy flows through ecosystems (Idea e) is restated in the chapter that deals with cellular respiration but not connected to the idea that energy transformations in ecosystems result from energy transformations in millions and millions of cells. Similarly, little effort is made to associate energy transformations in living systems with those in physical systems. Even though an earlier chapter shows that heat energy can be transformed into mechanical energy (course 2, Chapter 13: Energy Resources, pp. 392–394s), no effort is made to connect this to the energy transformations in cells.

Even with the above table, it is not possible to infer a logical sequence in the presentation of the key ideas. Although the claim is made in the introduction to the Teacher Wraparound Edition that “Science Interactions teaches concepts in a logical sequence from the concrete to the abstract” (p. 11T), this is not apparent from looking at the details of these specific key ideas. For example, Idea c4 is the first idea presented: “Fungi help decompose dead organisms and recycle the materials of which these organisms were made” (course 1, Chapter 8: Viruses and Simple Organisms, p. 273s). Yet, it is not until later in course 1 that the text mentions what some of these materials are (in reviewing the main points of Chapter 11: Ecology, the text states: “Many materials, such as water, oxygen, carbon dioxide, and nitrogen, are constantly being recycled through the environment” [p. 374s]). Another concern is the delay in discussing what food is (Idea a) until late in course 2 and the beginning of course 3, after the processes of food-making and breaking down (Ideas c, d) have been presented.

While numerous connections are made in each chapter, many of them are so superficial that the net effect may leave both students and teachers overwhelmed. Indeed, the teacher’s introduction states that the program will help teachers “Connect one area of science to another. Relate science to technology, society, issues, hobbies, and careers. Show your students again and again how history, the arts, and literature can be part of science. And help your students discover the science behind things they see every day” (p. 11T). This may be the case, but it is not an approach that is likely to help students focus on an important set of ideas.

However, the inclusion of the photosynthesis reaction as an example of an endothermic reaction in course 2, Chapter 18: Chemical Reactions does not seem superficial. This is presented after students have observed a reaction in which heat is absorbed. One might ask why endothermic reactions are presented before exothermic reactions are (given that most students are probably more familiar with energy-yielding reactions) and why cellular respiration is not presented as an example of an energy-yielding reaction. Nonetheless, the inclusion of this life science example in a physical science chapter is not seen in materials often. (One also can wonder why the terms “endothermic” and “exothermic” are needed, but that issue is considered in the instructional analysis.)

Beyond Literacy

The main chapters that treat the key life science ideas of matter and energy transformations (course 1, Chapter 10: Plant Life, and Chapter 11: Ecology; course 2, Chapter 19: How Cells Do Their Jobs; and course 3, Chapter 11: Fueling the Body) contain some content that goes beyond the level of sophistication of the key ideas. For example, course 1, Chapter 10 includes topics such as plant classification (pp. 316–321s) and plant reproduction (pp. 322–330s) that are outside the scope of science literacy as defined in Benchmarks for Science Literacy (American Association for the Advancement of Science, 1993) and National Science Education Standards (National Research Council, 1996). Even sections that treat key ideas on matter and energy transformations include investigations that are not related to the key ideas (e.g., chromatography of leaf pigments [pp. 332–333s] and opening and closing of stomata [pp. 334–335s]). Still other investigations focus on less sophisticated version of the key ideas, which students will likely have studied in earlier grades. For example, course 1 includes an investigation of what owls eat (chapter 11, pp. 354–355s) that focuses on what eats what rather than on the transformations of matter and energy that are involved. Although, overall, the content that exceeds the key ideas in these chapters is not excessive, it is interspersed with them; hence it may distract students from focusing on the key ideas.


The evaluation teams developed a summary assessment of the most common kinds of errors found in each of the three subject areas—physical science, Earth science, and life science. In this context, “errors” is taken to mean not only outright inaccuracies, but also those instances in which the material is very likely to lead to or support student misconceptions. Overall, inducement to misconstrue is the most serious problem of accuracy in the evaluated materials.

The teams’ collective findings, presented below, should be taken as having general applicability to all of the evaluated materials, not complete and specific applicability in toto to any one of them.

Identified errors occur most frequently in drawings and other diagrams. They take the form of representations that are likely to either give rise to or reinforce misconceptions commonly held by students. Following are life science examples of the kinds of misleading illustrative materials of most concern to the evaluation teams:

  • Diagrams of energy pyramids that indicate decreases in energy (without indicating that the energy is given off as heat) can reinforce students’ misconception that energy is not conserved.

  • Diagrams and explanations that show the reciprocal nature of respiration and photosynthesis can reinforce the misconception that only animals respire—and that plants do not. Furthermore, emphasizing the notion that these processes are reciprocal or balance one another fails to convey that the rate of photosynthesis is far more than that of respiration. Consequently, plants produce enough food (and oxygen) during photosynthesis both for their own needs and for the needs of other organisms.

  • Diagrams of nutrient cycles in biological systems, such as the carbon-oxygen cycle or the nitrogen cycle, often misrepresent the transformation of matter—showing, for example, atoms of carbon in one form but not in others. By failing to show a particular element throughout the cycle, a text can reinforce the misconception that matter can disappear in one place and reappear in another, as opposed to simply changing forms.

The use of imprecise or inaccurate language is problematic in text and teacher materials, not solely in illustrations. In life science, one significant problem is that imprecise language in explanations of energy transformations can reinforce students’ common misconception that matter and energy can be interconverted in everyday chemical reactions. For example, presenting the overall equation for cellular respiration in which energy appears as a product without indicating where the energy was at the start can lead students to conclude that matter is converted to energy. Similarly, presenting the overall equation for photosynthesis in which energy appears only as a reactant can lead them to conclude that energy has been converted into matter.