Earth Science | Life Science | Physical 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. |
[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
b: Several processes contribute to changing the
Earth’s surface.
Idea
c: The processes that shape the Earth today are
similar to the processes that shaped the Earth
in the past.
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.
Idea
e: Slow but continuous processes can, over very
long times, cause significant changes on the
Earth’s surface. The idea of slow change also is implicit
in a few activities. For example, the Using Math section (p. 301s) asks students
to calculate how far apart North America and
Africa will be in 200 million years. Similarly,
the second item 4 of Activity 11-2 (p. 306s) has students determine when Africa
was at or near the Mid-Atlantic Ridge.
In both cases, though, the material focuses on continental movement and not
on the key idea that small and slow but continuous changes to the Earth's
surface result in significant changes over time.
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. The text includes relevant activities. For example, some
students use clay to make models of continents and place
objects that represent fossils in the clay, while other
students try to reconstruct the continents' original locations
(p. 296s).
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. Chapter 11: Plate
Tectonics also provides activities, demonstrations, and
practice questions. For example, students are asked to calculate
spreading rates at the Mid-Atlantic Ridge (p. 306s) and,
after studying Figure 11-10, to illustrate the different
plate boundaries (p. 308st).
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 idea is addressed and represented in Chapter
9: Earthquakes and Chapter 10: Volcanoes. Two figures (9-2
on page 237s; 10-3 on page 268s) show the location of earthquakes
and volcanoes in relation to plate boundaries. Additionally,
in Chapter 11: Plate Tectonics, Figure 11-10 (pp. 308-309s)
explicitly relates divergent and convergent plate boundaries
to landforms of mountains, rift valleys, mid-ocean ridges,
volcanic island arcs, and trenches. Many of the landforms
and geologic events that occur as a result of tectonic plate
movement are discussed in the text (particularly on pages
304-313s). For example, students read about the Himalayan
and Appalachian mountains being formed by converging continental
plates (p. 312s). The Teacher
Wraparound Edition includes questions for students,
such as: "Earthquakes are associated with some plate boundaries.
Why do you think this is so?" (p. 311t).
Although several important pieces of evidence for continental drift are presented, the argument that links them to the conclusions is not explained in sufficient detail to be understood by students. In some places in the student text, alternative explanations for the evidence for continental drift are refuted, but the arguments are incomplete. For example, the text notes that Mesosaurus fossils have been found in South America and Africa and that "this swimming reptile lived in fresh water and on land..It's very unlikely that it could have swum between the continents" (p. 295s). However, it does not explain why. Such information as the small size of the reptile and the fact that ocean water is salty, which is a deadly environment for freshwater organisms, would have helped students to understand why the alternative explanation does not fit. Similarly, the text does not explain why it is unlikely that the Mesosaurus could have evolved independently in both locations. Similarly, the text explains that "[f]ossils of warm-weather plants were found on the island of Spitzbergen in the Arctic Ocean. Wegener believed that Spitzbergen drifted from the tropic regions" (p. 296s). Although the text states both the evidence and Wegener's conclusion, it does not make the argument for how the two are linked. Specifically, it 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, namely, Arctic and tropical regions. Furthermore, while it is possible that Arctic could have had a tropical climate in the past, the more plausible explanation for this (and other) evidence is that landmasses can move great distances.
Likewise, the motion of plates is used to discuss earthquakes and volcanoes in Chapters 9: Earthquakes and Chapter 10: Volcanoes, but it is not defined or explained until Chapter 11: Plate Tectonics. An earthquake activity (9-1 on pages 242-243s) begins by telling students that they have learned about plates already, even though plates are not taught until chapter 11 (p. 304s). The purpose of Activity 9-1 is to have students plot earthquake depths and then "hypothesize what is happening to the plates at the Earth's surface in the vicinity of the plotted earthquake foci." However, students will not understand the activity or the real phenomenon it represents, nor will they comprehend the connection between the depth of earthquakes and plate movement, because the necessary plate tectonic information is not taught until much later. Many other parts of chapters 9 and 10 involve the use and understanding of plate tectonics before students have had opportunities to learn about it (e.g., p. 243st, Go Further; p. 271st, Analyze and Apply, item 3; p. 272t, Reteaching; p. 272s, Figure 10-4; and p. 273st, Section Wrap-up, items 1 and 3, and Skill Builder).
The coherence of the Earth science ideas presented in this material is diminished further by extraneous topics that seem to have been inserted into chapters randomly. In Chapter 7: Erosional Forces, some activities in the Teacher Wraparound Edition bring in the topic of climate change (pp. 182-183t). Another activity has students research Bowen's reaction series and then write a report about why some magmas are hotter than others (p. 277t). This activity introduces a topic that is well beyond science literacy and may be difficult for middle grades students because it involves such complex ideas as chemical reactions, phase changes, and how the physical properties of mixtures differ from those of the individual components.
Overall, Glencoe Earth Science has a significant problem with presenting information in a logical sequence that will be comprehensible to students, allow them to make connections between concepts, and help them to understand how scientific ideas are developed. The frequent insertion of unrelated or conceptually difficult material into the flow of chapters is distracting and confusing to students. They may have difficulties connecting the considerable amount of highly detailed information provided with the overarching concepts stated in the key ideas.
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.