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Middle Grades Science Textbooks: A Benchmarks-Based Evaluation

Prentice Hall Exploring Earth Science, Exploring Life Science, and Exploring Physical Science. Prentice Hall School, 1997
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. The text asserts that the Earth is changing or has changed over time in several places (pp. 278s, 324–325s, 327s, 346–347s, 434s). A typical statement explains that, “[o]ver billions of years, the surface of the Earth has changed many times” (p. 278s), but does not provide any concrete examples. One suggested activity has students collect newspaper clipping about Earth-changing events over a two-month period (p. 330st).

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

There is a content match. While a general discussion of processes that shape the Earth is not included, several processes are presented (such as folding and faulting, volcanoes, earthquakes, wind erosion, water erosion, and glacial erosion). These processes are treated as separate topics, and are usually found in separate chapters. The text does not indicate that more than one process could affect the Earth at one time or place (for example, while mountains are being built up, they are also being eroded). Throughout this textbook, students make models of individual processes, such as folding mountains (p. 334s) and a stream table to show erosion (p. 476st). However, these activities and their accompanying reading sections tend to focus on the processes, not on the changes they bring about.

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. This idea is stated once in the text: “Hutton theorized that the processes acting on Earth’s surface today are the same processes that have acted on Earth’s surface in the past” (p. 595s). This statement is not further explained, and no examples, activities, or practice questions are provided.

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 partial content match. The following presentation of Idea d shows which parts of the idea are treated (in bold) and what alternative vocabulary, if any, is used (in brackets): Some of the processes are abrupt, such as earthquakes and volcanoes, while some are slow, such as the movement of continents and erosion. The text mentions a few slow Earth-changing processes, but does not discuss the time frame of abrupt processes. Examples of abrupt changes are provided (such as earthquakes and volcanic eruptions), but the focus is on the amount of damage and numbers of deaths that occurred as a result, rather than on the abruptness of the change. For example, photographs show the first few minutes of the Mount Saint Helen’s 1980 eruption (p. 359s), yet the rapid changes to the Earth (flattened mountain and several new layers of dirt and ash on the surrounding surface) are not mentioned in the text or caption. Slow processes, such as erosion and mountain building, are addressed in a few text statements. For example, the text states that “[m]ountains are built very slowly” (p. 280s) and that it took millions of years for the Colorado River to carve out the Grand Canyon (p. 454s). This key idea is addressed by a few practice questions (for example, “What is rapid mass wasting?” and “What is slow mass wasting” [p. 456st]), but not by any activities.

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

There is no content match. Although slow Earth-changing processes are mentioned in the text (see the discussion of Idea d above), the text does not explain that small, seemingly unnoticeable changes over long time frames can result in large changes to the surface of the Earth. Students are told that mountain building, the motion of tectonic plates, and erosion occur over millions of years, but the material does not state explicitly that these small changes add up to large differences. Small yet abrupt changes, like the mountains created by a series of earthquakes over a period of millions of years, are not addressed.

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. This idea is presented in Chapter 12: Plate Tectonics, in the context of describing the historical evidence for the continental drift hypothesis; namely, that similar fossils, such as Glossopteris, and similar rock layers have been found in now widely separated continents. The text states, “Glossopteris fossils, which are located in rocks about 250 million years old, are found in South Africa, Australia, India, and Antarctica” (p. 373s). Rock evidence is presented as well: “An ancient folded mountain chain that stretches across South Africa links up with an equally ancient fold mountain chain in Argentina” (p. 374s). Also, glacial features and rock deposits are provided as evidence for continental drift as well (pp. 374–375s). Three activities are included that could address this key idea. In one, students tear newspaper sheets into pieces and use the text to realign the pieces (p. 372st). This activity includes questions that ask how putting the pieces of newspaper back together is related to continental drift. In the second activity, students make cutouts of the continents and try to reassemble Pangaea (pp. 374s, 375t). The third activity asks students to explain how Wegener’s theory made sense of fossil evidence, and it includes practice questions about how Wegener’s theory used each of the different kinds of evidence (Teaching Resources, chapter 12 booklet, p. 10).

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. This idea is addressed in Chapter 12: Plate Tectonics. The text provides a definition of “plate” and discusses the theory of plate tectonics: “The word plate refers to the moving, irregularly-shaped slabs that fit together like paving stones to form the surface layer of the Earth” (p. 380s). The text explains that the plates move slowly: “Plates move at different speeds and in different directions. Some small plates that lack landmasses move as much as several centimeters per year. Large plates that are weighted down with continents move only a few millimeters per year” (p. 381s). Also, the three types of plate boundaries (divergent, convergent, and strike-slip) are discussed (pp. 382–383s).

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. The text provides many examples of landforms and geologic events that result from the motion and interaction of the Earth’s plates (for example, the Indonesian and Aleutian Islands and the Himalayan Mountains [p. 385s]). The text also provides explanations, such as: “The collision of plates at convergent boundaries causes tremendous pressure and friction. Severe earthquakes often result” (p. 382s). A few practice questions focus on categorizing and defining plate interactions (convergent, divergent, and strike-slip boundaries). For example, a Concept Mastery question asks, “How do plate movements relate to volcanoes and earthquakes?” (p. 393s, item 1).

Building a Case

Most of the key Earth science ideas are presented as text assertions that are sometimes accompanied by illustrative examples. However, the text makes some attempt to build a case for the key idea that 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 (Idea f). This key idea states the evidence (matching coastlines, similarities in rocks, similarities in fossils) and the conclusion drawn from it (today’s continents are separated parts of what was a single vast continent long ago). In some places, the text provides an argument that explains why the evidence supports the conclusion. For example, after stating that Glossopteris fossils have been found in South Africa, Australia, India, and Antarctica, the text points out that the seeds are too large to have been carried by the wind and too fragile to have survived a trip by oceans’ waves. That is, the text refutes alternative explanations—before stating the conclusion: “This suggests that the places in which the plant’s fossils are found must once have been closer together” (p. 373s). In other places, the text does not provide an argument that links the evidence to the conclusion. For example, the text states that finding Glossopteris fossils in Antarctica (the evidence) “indicates that Antarctica’s climate millions of years ago was far different from the way it is today” (p. 374s) (the conclusion). However, the text does not explain why finding the same fossil in now quite different climates requires an explanation. For example, the text does not point out that an organism is typically suited for only one type of climate so it is unlikely that the same organism would have existed in such different climates as those of South Africa, Australia, India, and Antarctica. And given that fossils typically are found where organisms once lived, it is likely that these locations once had the same climate. And while it is possible that widely separated regions could have the same climate, the most plausible explanation for this (and other) evidence is that the regions were once in close proximity. In another instance, the text presents an argument and the conclusion but fails to adequately describe the evidence:
Many glacial deposits are found in South America, Africa, India, Australia, and Antarctica. The similarity of these deposits indicates that they were left by the same ice sheets. Many of these ancient glacial deposits have been found in areas with very warm climates. Because glaciers usually form close to the poles, scientists have concluded that these areas were once part of a giant landmass located near the South Pole. [p. 374s]

The text does not describe the similarities in the deposits and does not explain why such similarities are unusual. (After all, students probably have made ice cubes in several different freezers and haven’t observed differences among the ice cubes.)


The key ideas about the processes that shape the Earth’s surface are addressed in Exploring Earth Science in five chapters (10, 11, 12, 14, and 15) in Unit 3: Dynamic Earth. One prerequisite, namely, familiarity with land features, is found in Chapter 8: Earth’s Landmasses in Unit 2: Exploring Planet Earth. However, in Prentice Hall’s modular version of Exploring Earth Science, entitled Prentice Hall Science, these key ideas are presented in the Dynamic Earth module, with the prerequisite ideas about landforms being given in a different module, Exploring Planet Earth. Whereas the material is presented in a set sequence in the textbook, the corresponding modules are unnumbered and Prentice Hall neither recommends any particular order nor alerts teachers to what prerequisites are given in individual modules. Consequently, it is possible for students using the modules to study the processes that shape the Earth before they have gained familiarity with the Earth’s landforms.

Although many experiences and examples of most of the key ideas are given, almost no attempt is made to tie together all the experiences provided for any of the individual key ideas or to relate key ideas to one another. For example, the material presents many processes that shape the Earth (streams, glaciers, wind, mountain building, volcanoes, and earthquakes), but there are no statements, questions, or activities that focus students’ attention on the fact that several of these processes often act at the same time on the same land feature, such as mountains being built up at the same time erosional forces are at work tearing them down. Furthermore, although Chapter 12: Plate Tectonics provides examples of landforms created by the interactions of the Earth’s plates, these examples are not linked to the individual processes of mountain building, volcanism, or earthquakes as described in the previous two chapters.

Few if any relevant connections are made to ideas outside this set of key Earth science ideas. Although this material recommends the use of models to show Earth processes, the opportunity to connect the use of these models to the role of models in science is not taken.

Beyond Literacy

The chapters examined include several topics that are beyond 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). In a few cases, more advanced ideas are presented. For example, the discussion of moving tectonic plates includes an explanation of magnetic evidence for moving plates (pp. 376–380s). This discussion is neither necessary nor likely to be comprehensible to students. A similar problem is found with the discussion of the chemical composition of different types of lava (pp. 357–358s). But more often, the text explanations include so many details of Earth-changing processes that the more general ideas are obscured. For example, in Chapter 10: Movement of the Earth’s Crust, students read about compression, tension, shearing, fractures, faults, hanging walls, foot walls, normal faults, reverse faults, thrust faults, lateral faults, folds, anticlines, synclines, and more (pp. 328–337s). Similarly, in Chapter 15: Erosion and Deposition, students are bombarded with technical terms that label such glacial formations as moraines, till, drumlins, meltwater, outwash plains, and kettle lakes (pp. 466–470s). And, as students are reading about wave erosion, their focus is diverted to such phenomena as sea cliffs, sea terraces, sea stacks, sea caves, longshore currents, sand bars, and spits (pp. 470–474s). Such attention to labels and technical terms is not called for in Benchmarks for Science Literacy or National Science Education Standards, and unfortunately it will cloud the more general understanding of how the Earth is shaped and reshaped over time.


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.