Browse science textbooks

Macmillan/McGraw-Hill Science. Macmillan/McGraw-Hill School Publishing Company, 1995

Life Science

1.
About this Evaluation Report

2.
Content Analysis

3.
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.

Building a Case

[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.

Coherence

[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.

Beyond Literacy

[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.

Accuracy

[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.

References

Alignment

Idea a: Food (for example, sugars) provides molecules that serve as fuel and building material for all organisms.

There is a content match. This key idea is treated in terms of substances but not molecules. Several statements indicate that the material intends that students should know the idea that food provides building material for organisms. In Earth’s Ecosystems (p. 66a), teacher’s notes indicate that a common student misconception is that consumers get only energy from food, whereas they also get materials. Teachers are instructed to convey to students that consumers get materials as well (p. 74t). In the same unit, teacher’s notes suggest that teachers burn a peanut or dried meat and use the energy released to heat water to demonstrate that food provides energy (p. 71t). In Changes in Ecosystems, the text mentions the idea that “Different kinds of food have different amounts of energy stored in them. Humans need a variety of food to obtain all the materials they need for their bodies to function properly” (p. 40s). The small number of other statements identified (e.g., Earth’s Ecosystems, p. 67t, Minds On!) were not explicit about this key idea.

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

There is a content match. The contrast between plants making their own food and animals having to consume food is treated explicitly in The Plant Kingdom and then used in the context of distinguishing producers from consumers in Oceans in Motion. For example, in The Plant Kingdom, teachers are instructed to ask students how plants differ from animals in the way they obtain food, and the suggested response given is that “plants are producers, animals are consumers” (p. 32t). The text then emphasizes this distinction (The Plant Kingdom, p. 33s), and Discussion Strategies suggest that teachers discuss the distinction with students:

Discuss with students what plants need, and compare their needs to those of animals. (Plants don’t need food as such. They need water, carbon dioxide, and sunlight to help them make their own food. Animals must consume food that is produced by plants or eat other animals that have eaten plants.) (p. 45t)

However, other places in the text that involve students in identifying producers and consumers and in examining or constructing food chains were not considered to be content matched because they do not involve students in making explicit the distinction between producers and consumers—the heart of this key idea.

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. In both The Plant Kingdom (in the context of photosynthesis) and Earth’s Ecosystems (in the context of the carbon cycle), text and discussion questions focus on the conversion of carbon dioxide and water to sugar. In the context of photosynthesis, text and suggested answers to discussion questions emphasize using something to make something (e.g., The Plant Kingdom, pp. 36s, 38s, 41s, 49s, 40-41t), whereas, in the context of the carbon cycle, the emphasis is on converting something into something else (e.g., Earth’s Ecosystems, pp. 14t, 21t, 17s). But both statements reflect attempts to convey that matter is transformed. However, several other statements in The Plant Kingdom focus on only a single component of the photosynthesis equation but do not emphasize the transformation of matter. (In Simple Organisms and Viruses, there is something that could confuse students. On page 25t, teachers are to ask students to describe the change that occurs during photosynthesis. The response given, “Organisms use energy from the sun to produce food and release oxygen,” confuses matter and energy by failing to indicate that the food and oxygen are made out of other materials—carbon dioxide and water—not out of the sun’s energy. An activity is included in which students explore plants’ use of carbon dioxide in the light and dark, but the emphasis is on the use of carbon dioxide, rather than on the transformation of matter (The Plant Kingdom, pp. 34-35s).

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 content match. Parts of this idea are treated in two different units—The Plant Kingdom and Earth’s Ecosystems, exclusively in the text or the teacher’s notes. In the context of describing the process of photosynthesis, the text states that food not used immediately by plants is stored (The Plant Kingdom, p. 38s). After examining the ingredients in “plant food” and distinguishing those ingredients from the sugar produced in photosynthesis, teacher’s notes indicate that “Students should conclude that the ingredients in plant food help the plants form cell-building materials…” (The Plant Kingdom, p. 44t). In the context of integrating physical science, teacher’s notes state that “Organisms…break down chemical compounds into simpler elements…recombining them into other compounds…[to] use for growth or metabolism” but does not make clear that plants are organisms (Earth’s Ecosystems, p. 74t). (One activity, intended for use at home as a family science activity, is supposed to address the idea that plants produce water and carbon dioxide during cellular respiration. Students put plastic bags over tree branches and observe that water appears. However, the water that students will observe is more likely the result of the condensation of water that has evaporated from the leaf following transpiration, rather than respiration [Earth’s Ecosystems, Teaching Resources, p. 1a].)

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 content match. Most of this key idea is presented in the student text, although only one note in the Teacher’s Guide deals with the reassembly of digestion products into body structures. The concept that food is broken down during digestion is introduced in an activity in which students simulate the action of a bird gizzard (The Animal Kingdom, p. 56s). The discussion that follows focuses on the mechanical breakdown of food, but not on the chemical breakdown and reassembly. Subsequent text describes the passage of food through the digestive system of various species, indicating that food is “changed physically and chemically so that its nutrients can be absorbed” (The Animal Kingdom, p. 57s). While the text indicates that not all of the digested food is usable and that the unusable remains are excreted, it is not explicit about the part that is usable being reassembled into the bird’s own body structures. A few other statements deal with the idea that body structures are formed from food, but they do not get at the more sophisticated idea that forming body structures involves the reassembly of components of digested food as this key idea does (Earth’s Ecosystems, p. 66a). In only a single mention is the idea of reassembly explicit. The teacher notes for integrating physical and life sciences: “Organisms…break down chemical compounds into simpler elements,…recombining them into other compounds…[to] use for growth or metabolism” (Earth’s Ecosystems, p. 74t).

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

There is a content match. It is addressed through both text and discussion questions in Simple Organisms and Viruses, in the context of describing the decomposing role of bacteria (pp. 21-22s); in Oceans in Motion, in the context of ocean food webs (pp. 71-73s); in Earth’s Ecosystems, in the context of the carbon and nitrogen cycles (pp. 21-23t); and in Changes in Ecosystems, in the context of the role of decomposers in composting (pp. 23–24s). This idea is also the focus of several reflection and assessment tasks (e.g., Oceans in Motion, p. 83s; Earth’s Ecosystems, p. 66d; Changes in Ecosystems, p. 27s).

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. This key idea is presented mainly in the student text, although the part of the idea that sugars are “energy-rich” is mentioned only once in the student text. Primarily in The Plant Kingdom (but also in Oceans in Motion and Earth’s Ecosystems), both the text and the answers to discussion questions state the idea that plants use light energy to make sugar (e.g., The Plant Kingdom, pp. 38s, 44s, 49s; Oceans in Motion, p. 82t; Earth’s Ecosystems, pp. 70-71s). However, while such statements as, “Plant leaves use their own chlorophyll and sunlight as energy to make food…” (The Plant Kingdom, p. 32a) or “Recall that photosynthesis is the process plants use to produce food using energy from light” (Simple Organisms and Viruses, p. 25s), convey the idea that light is used to make sugar, they do not convey the idea that some of the energy is stored in the sugar. To students, “used” may be interpreted as “used up.” The idea that sunlight is transformed into another form of energy—chemical energy—is stated explicitly only once, in Earth’s Ecosystems (p. 74s), although it is implicit in the statement: “Plants get energy from food through the process of respiration…. Sugar and oxygen are the end products of photosynthesis. Plants and animals use the end products of photosynthesis to produce energy through respiration” (The Plant Kingdom, p. 44s). As noted above (see the discussion for Idea c₁), an activity is included in which students explore plants’ use of carbon dioxide in the light and dark, but the emphasis is on the use of carbon dioxide, rather than on the transformation of energy (The Plant Kingdom, p. 34s).

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

There is a content match. Parts of this idea are treated separately in two different units. In The Plant Kingdom, the idea that plants obtain energy from respiration is addressed in the text (pp. 44s, 49s), teacher’s notes (pp. 32a, 32d), and student assessment (p. 32d). The idea that energy is lost as heat is stated in the teacher’s notes that accompany the text discussion and illustration of an energy pyramid: “Whenever energy is converted from one form to another, some is lost, usually as heat. That is why there are always fewer consumers in an ecosystem than producers” (Earth’s Ecosystems, p. 74t). However, the idea of heat loss is not included in the student reading.

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. This key idea is addressed in The Animal Kingdom, in the context of digestion and cell respiration (pp. 54–55s), and in Earth’s Ecosystems, in the context of energy transfer in food chains (pp. 71t, 74t). The idea that glucose is broken down to release chemical energy is treated mainly in the text and notes for teacher-led discussions. However, it is suggested that teachers demonstrate that burning a nut or piece of dried meat will heat up water to convey the idea that the chemical energy in food heated up the water (Earth’s Ecosystems, p. 71t). It is assessed in Changes in Ecosystems (p. 23s), although expecting students to infer from observing bread turn black and get soggy that the mold is using the bread to obtain energy and, in the process, the bread is being broken down requires quite a leap from the observation.

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. Matter cycling is treated in Earth’s Ecosystems in the context of the carbon and nitrogen cycles (pp. 21-23s), and energy flow is treated in the context of food chains in the same book (pp. 70–71s). These ideas are stated clearly in the text and are the focus of discussions (Earth’s Ecosystems, p. 73t) and student tasks (Earth’s Ecosystems, p. 67s). (Not all mentions of food chains were considered on target, because they focused on what eats what, rather than on the transfer of matter or energy.)

Building a Case

No attempt is made to provide an evidence-based argument for any of the key life science ideas.

Coherence

The Macmillan/McGraw-Hill program as a whole does not relate its presentation of the individual ideas either explicitly in the text or through tasks or questions for students. The ideas are treated as bits of isolated information in several different units that are organized around topics, rather than around a coherent set of important ideas. There is no obvious conceptual sequence to the units, nor is one conveyed to the teacher. While, in some cases, the text mentions that students have had some experience with an idea—for example, after saying that cyanobacteria photosynthesize, the text reminds: “Recall that photosynthesis is the process plants use to produce food using energy from light” (Simple Organisms and Viruses, p. 25s), and before describing ocean food webs, the text states: “You’ve probably learned about food chains and food webs that exist on land” (Oceans in Motion, pp. 72-73s)—this is not done systematically, nor is the experience described specifically. More commonly, no conceptual links are made between units; for example, the role of decomposers is presented in the context of land ecosystems (Earth’s Ecosystems, pp. 20-32s) but not linked to presentations in Simple Organisms and Viruses (pp. 21-22s) or Oceans in Motion (pp. 72-73s).

Teacher’s notes at the beginning of each book describe how the program integrates the sciences:

Instead of limiting the study of a topic or concept to one science, students make the connections to other science contexts. By exploring these connections, they are able to understand the topic or concept in more depth. [Simple Organisms and Viruses, p. T–6]

However, while the textbooks reviewed treat other, related, benchmark ideas, they rarely make definite connections between them and the ideas serving as the basis for this analysis. In a couple of instances, connections are noted but are not well developed. For example, in The Plant Kingdom, the connection between plants making food and systems is noted. Students are told: “In this lesson, you'll learn how plant cells work together as systems to produce and use food” (The Plant Kingdom, p. 32s). The teacher’s notes suggest that students be asked how other systems interact, but no guidance is given about what should come out of the discussion (The Plant Kingdom, p. 32t). Furthermore, no link is made to the related idea that “thinking about things as systems means looking for how every part relates to others” from Benchmarks for Science Literacy (American Association for the Advancement of Science, 1993, p. 265).

Beyond Literacy

When treating matter and energy transformation in life science, the material sometimes includes content that goes beyond the science literacy recommendations of Benchmarks for Science Literacy and the National Research Council’s National Science Education Standards. For example, in describing how water gets to cells, The Plant Kingdom uses the terms “root hairs,” “osmosis,” “xylem,” “phloem,” and “petioles” in a single paragraph (p. 29s).

Accuracy

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.

1.	About this Evaluation Report
2.	Content Analysis
3.	Instructional Analysis

Middle Grades Science Textbooks: A Benchmarks-Based Evaluation