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AAAS  :: Project 2061  :: Textbook Evaluations

Middle Grades Science Textbooks: A Benchmarks-Based Evaluation

Macmillan/McGraw-Hill Science. Macmillan/McGraw-Hill School Publishing Company, 1995
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 in support of 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: The surface of the Earth is changing continually.

There is a content match. Several statements in the student text explain that the Earth or surface of the Earth is changing continually. For example, one unit opener explains that

the forces that sculpt, or change, Earth’s rocky surface never complete their work. Around the clock, rivers pick up rocks, carry then along, change them, and put them down somewhere else. Day and night, wind blows against rock, grinds them down and carries them off. Inside Earth, processes work unceasingly to create rocks or change them. [Earth’s Solid Crust, p. 6s]

This idea is discussed in other contexts, such as mapmaking and land features in national parks (Unit 35: Earth’s Solid Crust, pp. 58–59s, 71s, 80s, 91s; Unit 40: Earth Changes Through Time, p. 108s).

Idea b: Several processes contribute to changing the Earth’s surface.

There is a content match. Several Earth-shaping processes are discussed. For example, one unit opener explains that “Sometimes Earth's agents of change work in dramatic and visible ways, such as volcanic eruptions; other times they occur in unseen ways like the erosion of rocks by the imperceptible motion of a glacier” (Earth’s Solid Crust p. 6s). Volcanic eruptions, earthquakes, wind, water, and glacial erosion are specifically presented (Earth's Solid Crust, pp. 58–60s, 60–63s, 64–65s; Earth Changes Through Time, pp. 58–59s, 76–80s). These discussions focus on the mechanism of the process but not on how the surface of the Earth changed as a result of the process. Many of the activities have students model processes that change the surface of the Earth, such as make a stream table (Earth's Solid Crust, pp. 52–53s) and model wind erosion (Earth's Solid Crust, p. 64s). However, these activities and the accompanying questions do not focus students' attention on how the processes change the surface of the land.

Idea c: The processes that shape the Earth today are similar to the processes that shaped the Earth in the past.
There is a content match. The student text explains that scientists assume that the Earth-changing processes seen today are the same processes that have operated in the past. The text provides a simple example: “If gravity causes a rock to fall from your hand to the ground today, you can assume that if you had been around 20 million years ago, gravity would have caused a rock to fall to the ground then” (Earth's Changes Through Time, p. 17s). Then, an example of an Earth-shaping process is given. The text explains that, “If water flows downhill today, it is safe to assume that it has flowed downhill ever since water started flowing” and that, “If you found an ancient river, you could assume that its banks eroded in some places and sand was deposited in other places, too” (Earth's Changes Through Time, p. 17s).

Idea d: Some of the processes are abrupt, such as earthquakes and volcanic eruptions, while some are slow, such as the movement of continents and erosion.

There is a content match. Some examples of abrupt and slow Earth-changing processes are provided. The nine-year formation of Mount Parícutin is presented as a relatively quick change to the surface of the Earth (Earth Changes Through Time, p. 80s). Earthquakes are mentioned as occurring suddenly, but the focus is on the damage to cities and the human death toll, rather than on the changes to the surface of the Earth (Earth Changes Through Time, p. 55s). The slow erosion at Bryce Canyon and Arches National Park are described as occurring over millions of years (Earth's Solid Crust, pp. 58–59s, 69–71s). Although abrupt and slow processes are presented, the time frames of Earth-shaping processes are not compared. One Minds On! activity asks students to list and discuss rapid and slow changes to the Earth (Earth Changes Through Time, p. 99s).

Idea e: Slow but continuous processes can, over very long times, cause significant changes on the Earth’s surface.

There is a content match. Two examples of slow changes over long time frames are provided. The text explains that:
Flash flooding, combined with the effects of wind and other agents of erosion, cause the rim of the canyon [Bryce Canyon] to erode at the rate of 30 centimeters (1 foot) every 50 years. Over millions of years, water has eroded the limestone, sandstones and shales in Bryce Canyon to form a fantastic collection of spires and craggy columns. [Earth's Solid Crust, p. 59s]

The landscape at Arches National Park is described as being created over a long time period as well, but the slow process of change is not explained explicitly: “Windblown material, precipitation, and runoff subjected the sandstone to weathering and erosion for millions of years. Gradually, these agents of change carved holes in the sandstone” (Earth's Solid Crust, p. 69s). Lastly, although the slow rate of motion of the tectonic plates is not mentioned in the text, a side feature called Math Link asks students to calculate how long it will take Los Angeles to move to San Francisco (Earth Changes Through Time, p. 96s).

Idea f: Matching coastlines and similarities in rocks and fossils suggest that today’s continents are separated parts of what was a single vast continent long ago.

There is a content match. The text explains that similar fossils found on now widely separated continents and similar rock columns located in Brazil and Africa are evidence for a single ancient continent. An activity has students trace and cut out the shapes of continents, draw surface features (rocks and fossils), and arrange them by first matching shapes alone, then shapes and surface features (Earth Changes Through Time, pp. 46–47s). Another activity has students look at two continents on a fictitious planet and decide if continental drift is taking place there based on similar evidence (matching coastlines and similar land features). A few questions also focus on this idea. Students are asked to recall Wegener's most obvious piece of evidence and to determine what sorts of evidence would be needed to conclude that continental drift is occurring on Venus (Earth Changes Through Time, p. 53s).

Idea g: The solid crust of the Earth consists of separate plates that move very slowly, pressing against and sliding past one another in some places, pulling apart in other places.

There is a content match. The text provides a definition of plates and plate tectonics as well as a map of the major plates (Earth Changes Through Time, p. 88s). An activity has students use the broken shell of a hard-boiled egg to model plate interactions, while the following text describes the three ways in which plates interact (Earth Changes Through Time, p. 89st). A photograph of pillow lava is shown and discussed as a feature found at ocean ridges (Earth Changes Through Time, p. 92t).

Idea h: Landforms and major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.

There is a content match. Some examples are given of landforms and geologic events that occur at plate boundaries, such as the San Andreas Fault in California and the East African Rift Valley (Earth Changes Through Time, pp. 89s–90s). One activity has students plot the depths of earthquakes in South America; they are told later that the increasing depth showed that one plate was sliding underneath another one. A Minds On! activity near the end of the unit asks students to look at the map of the plates and predict where the next mountains will be formed (Earth Changes Through Time, p. 108s).

Building a Case

Most of these key Earth science ideas are asserted by the text, while activities allow students to verify or exemplify them. However, an evidence-based case is presented for the idea that matching coastlines and similarities in rocks and fossils suggest that today’s continents are separated parts of what was long ago a single vast continent (Idea f). Several lines of evidence are explained. The student text explains that similar rock layers and matching fossils have been found on now far spread continents and that fossils of tropical organisms have been found in Antarctica. Not only does the text present this evidence, but it also explains the significance of the evidence and why it is inconsistent with alternative explanations. For example, to appreciate the fossil evidence, students need to understand that it is very unlikely for organisms to develop in exactly the same way in separate environments. This is explained in the student text:
Fossils provided further evidence. They showed that, long ago, the same plants and animals existed on different continents at the same time. This is quite unusual because, as you know, specific plants and animals are limited by their habitats and their environments. Finding the same animal or plant in both Africa and South America would imply that they had, at one time, closely similar environments. [Earth Changes Through Time, p. 48s]

Furthermore, the text explains that the seeds for the Glossopteris plant (fossils of which have been found in India and Australia) were too big for the wind to blow them across an ocean and that it is unlikely that the same plant would develop in exactly the same way on isolated, separate continents. Similarly, the evidence for matching rock layers is presented and explained:

First, the rock record on the boundaries of different continents was observed, analyzed, and interpreted. The beds of rock, you recall, allow us to interpret the history of Earth at that place. Dating of rocks can tell us about when they formed…. In many places, older rock layers along continental boundaries matched well. Recently formed layers showed differences. (In terms of Earth’s history, a 100-million year old rock is recent.) The differences could represent what happened after the continents split apart. [Earth Changes Through Time, p. 48s]

Lastly, the fossils of tropical organisms found in Antarctica, which now has a cold climate, are explained: “What did this evidence mean? At one time, this region must have been much warmer. At that time it was located near the equator, where such plants and animals live” (Earth Changes Through Time, p. 49s). Then, these lines of evidence are related to the conclusion: “The fit of the continents, the similarities of the rock record, fossils of similar plants and animals, and evidence of similar climates were the clues scientists had” (Earth Changes Through Time, p. 49s).

Furthermore, students are given a chance to think about some of the evidence. At the end of the continent-matching activity, students are asked several questions such as, “What does the evidence of fit for shapes and features tell you about the continents and their relative positions?” and, “If you lived 10 or 20 million years from now, how would you be able to figure out the relative positions of the continents of the 20th century?” (Earth Changes Through Time, p. 47s).


The Macmillan/McGraw-Hill Science program presents all of the key Earth science ideas and in most cases provides real world examples. In some instances, the text attempts to link the ideas to one another. For example, in the context of explaining the formation of Bryce Canyon, the text states that water continually changes the land features, creating some and destroying others, and explains that this process sometimes occurs little by little over long periods of time (Earth’s Solid Crust, pp. 58–59s). This explanation links the idea that the surface of the Earth is changing continually (Idea a) to the idea that small, unnoticeable changes can accumulate over time to make significant changes on the Earth (Idea e). In another instance, the text explains that scientists believe that the processes we observe today are the same processes that occurred in the past and explains this in terms of the erosion of a river (Earth Changes Through Time, p. 17s). This explanation links the idea that explains uniformitarianism (Idea c) to the idea that several processes shape the surface of the Earth (Idea b).

However, although many experiences and examples for each idea are provided and some links are made between ideas, there is almost no attempt to tie together all the individual experiences provided for the key ideas. For example, information about the many processes (streams, glaciers, wind, volcanoes, and earthquakes) that shape the Earth is presented, but there are no statements, questions, or activities that focus students on the fact that several of these processes often act at the same time on the same land feature—as, for example, when mountains are built up at the same time that erosional forces are at work tearing them down.

Other coherence problems stem from occasional inappropriate topic sequencing and unrelated topics added. For instance, the text presents how water, wind, ice, and gravity all change landforms on the surface of the Earth (Earth’s Solid Crust, pp. 50–71s) even though the more general topic of “What are Landforms?” is not introduced until the next chapter (Earth’s Solid Crust, p. 76s). In another instance, a feature called Science, Technology and Society focuses on shoreline erosion (Earth’s Solid Crust, p. 48s), even though the process of erosion is presented in the following chapter. Interesting sidebar notes and activities are usually separated from the text by a box. However, sometimes the text is interrupted with interesting and unrelated facts, such as careers or myths and legends, making it more difficult to focus on the important Earth science ideas (e.g., Earth’s Solid Crust, pp. 37s, 39s, and Earth Changes Through Time, p. 82s).

Other connections to relevant ideas in science are made. For example, some of the key Earth science ideas are well connected to the role of models in science. The theme of models is used throughout the Earth Changes Through Time unit as the theory of plate tectonics is presented. In the unit introduction, the teacher is alerted to the Theme Connection of models (p. 6t) and students read that, “In order to understand Earth’s processes, you can create a model by making observations of changes and patterns on Earth” (p. 7s). Throughout the unit, the text describes how scientists have changed their model of Earth processes as new evidence is discovered. For instance, lesson 5 begins by explaining that, “In this lesson you will find out how the pattern of earthquake and volcano distribution helped geologists modify their model of Earth processes” (p. 70s). Similarly, lesson 6 begins with, “In this lesson you will see how all of the bits and pieces of evidence you’ve seen so far and some new pieces add up to give us our current models of Earth processes” (p. 84s). Although models are a unifying theme for the unit, there is little attention given to the models that students make in the activities throughout the unit. Many activities have students make models of Earth processes (e.g., Earth Changes Through Time, pp. 18s. 19s, 20s), yet students are not asked about the usefulness or limitations of their models or how different models can be used to represent the same thing.

Beyond Literacy

The Macmillan/McGraw-Hill Science series includes a few topics that are beyond science literacy, such as geologic time (Earth Changes Through Time, pp. 103–106s), the layers of the Earth (Earth Changes Through Time, p. 93s), and the magnetic data used as evidence for seafloor spreading (Earth Changes Through Time, pp. 92–93s).


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 evaluation 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 Earth science examples of the kinds of misleading illustrative materials of most concern to the evaluation teams:

  • Maps that do not show the accurate locations of earthquakes and volcanoes will prevent students from understanding the relationship between these events and plate boundaries. Likewise, diagrams and maps that do not include legends, and photographs that do not explain the size and scale of the object seen, are difficult for students to understand.

  • Diagrams that (a) depict plates moving away from one another, thus exposing the mantle, (b) show the mantle very close to the surface of the Earth, or (c) show plates as being a layer under the crust inaccurately represent the structure of the Earth and the motion of plates.

  • Diagrams that show the melting of subducted plates are incorrect. Subducting plates are known to cause melting in the mantle, and thus nearby volcanic activity, but the plates do not melt.