Some phenomena are provided that support the idea that increased temperature means greater particle motion (Idea d); however, phenomena are not provided that can be explained in terms of the expansion of solids or liquids. In addition, phenomena are presented for the idea that there are attractive forces among particles in liquids (part of Idea e₂). However, there is little variety, and most phenomena focus on surface tension. Very few experiences are presented to support the idea that particles are perpetually in motion (Idea c) or to illustrate changes of state (Idea f). No phenomena are included on the arrangement and motion of particles in solids, liquids, and gases (Idea e).

The choice of phenomena is a general weakness in level B's Unit 2: Why Are Things Different? Most phenomena included are too complex for middle school students (for example, the chemical reactions presented in chapter 9, or the surface tension phenomena presented in chapter 11).

With regard to this introducing-terms criterion, one review team gave the material an "excellent" rating, but the other team gave it a "very good" rating. Given the weakness in the material's introduction and use of the term "particle," the Project 2061 staff recommends a "very good" rating.

With regard to this criterion about demonstrating use of knowledge, one review team gave the material a "poor" rating, but the other team gave it an "excellent" rating. According to the second team, "The material does an outstanding job of demonstrating how to construct and critique a scientific explanation. This includes demonstrations of how to design an investigation, how to use ancient explanations to explain properties of materials, how to use observations as evidence in support of a model, how to revise a model on the basis of new information, how to make predictions on the basis of a model, how to construct if-then statements to express predictions made on the basis of a model, and how to critique a scientific explanation."

In response to this statement, the first team pointed out that students are asked to explain various phenomena in terms of the particle model, but they will not know how; rather, they are left to arrive at their own explanations. This evaluation focuses on whether Diversity and Limits provides instructional support for the idea that "all matter is made of particles" and not for students' ability to develop and use models. Consequently, to satisfy this criterion, the material needs to "demonstrate how to explain different phenomena using the particle model." Although Diversity and Limits attempts to demonstrate how to use models and points to what a good explanation or model is in general, it does not show students explicitly good examples of explanations using the particle model. Therefore, the Project 2061 staff recommends a "poor" rating for this criterion.

The rating given above for this encouraging-students criterion is the average of the ratings of the two review teams (the individual team ratings were "poor" and "satisfactory"). The teams debated the question of what students are asked to monitor in Diversity and Limits: their understanding of the particle model ideas (key ideas) or the usefulness of their models. The first team pointed out that students do not evaluate their ideas against what is known, that the progression of the particle model that the material suggests is not necessarily the one that the students would use, and that giving them the steps takes the self-monitoring out of their hands. The second team objected that the clarification of the criterion that was available to reviewers does not say explicitly that students need to check their own progress against "what is known."

This evaluation focuses on whether Diversity and Limits provides instructional support for the idea that "all matter is made of particles" and not for students' ability to develop and use models. Therefore, to satisfy this criterion, the material needs to engage students in monitoring their progress in understanding the particle model. While it is true that the clarification document does not state explicitly that materials need to encourage students to check their progress against "what is known," students appear to monitor mostly whether their models fit the observations at hand, and hence, whether the process they used to build their models was adequate (rather than whether the actual models, and hence, their understanding of the particle model are adequate). Therefore, the Project 2061 staff recommends a "fair" rating for this criterion.

None of the other key physical science ideas-such as the idea of different arrangement and motion of molecules in the solids, liquids, and gases (Idea e)-are assessed.

A few tasks could be used to assess students' progress in understanding the particle nature of matter (Idea a). One question asks students to describe the evidence scientists have for the particle model (level B, p. 241s, item 2). Other questions ask students to use the particle model to explain phenomena such as a coin placed on the rim of a bottle that moves when the bottle is placed in hot water (but not when placed in cold water) (p. 210s, item 14) and what happens when a flask filled with cold colored water is placed in hot water (pp. 210-211s, item 8). For questions like these, found in the Evaluate sections, the introductory material encourages teachers to ask questions such as "Why do you think.? What evidence do you have? What do you know about x? How would you explain x?" (p. xviiit). Unfortunately, teachers are not reminded of these questions in the Evaluate sections throughout the chapters, so this advice may go unheeded. Occasionally, teachers are reminded to motivate the students to provide supporting statements for their answers (e.g., p. 210t). However, overall, the material does not include suggestions for teachers about how to interpret students' responses, nor does it include specific suggestions about how to use students' responses to make decisions about instruction.

The material generally provides sufficiently detailed answers to questions in the student text for teachers to understand and interpret various student responses (e.g., pp. 204-205t, Wrap Up, item 2). However, there are some limitations to the responses provided in the teacher's notes, which occasionally are incomplete (e.g., p. 207bt, Wrap Up, items 5, 7).

The material provides minimal support in recommending resources for improving the teacher's understanding of key ideas. The Teacher's Edition includes a list of "Websites of Interest" with brief, bulleted descriptions and recommendations at the beginning of each chapter (e.g., pp. 191c-191dt) and a list of "Educational Technology Resources" (software, CD-ROMs, videos, and laser discs) with recommendations but not descriptions at the beginning of each unit (e.g., pp. 161b-161dt). A reference list subdivided by unit without annotations is also provided at the end of the Teacher's Edition (pp. 417-418t). Limited descriptions of references in the Teacher's Edition identify topics addressed, but none of the references are explicitly linked to specific text sections or key ideas. In addition, the Teacher's Resource Book has a Background Resources section that includes commentary on science standards documents and general references on learning and assessment strategies.

The material provides some suggestions for how to respect and value students' ideas. Teacher's notes often stress that multiple student answers should be acceptable for questions (e.g., p. 184t, Wrap Up). However, this may have implications for other criteria (see segment above entitled "Providing practice"). The skills identified as "Be open to others' ideas" (e.g., p. 192s, Working Cooperatively) and "Let others finish without interrupting" (e.g., p. 208s, Working Cooperatively) are stated in multiple places in the student text and teacher's notes as new cooperative group skills. However, other than stating the skills, the material does not usually provide students with any further support in how to enact the skills within their cooperative groups.

For the particle model of matter, the material provides many suggestions for how to raise questions such as, "How do we know?  What is the evidence?" and "Are there alternative explanations or other ways of solving the problem that could be better?" (e.g., p. 198s). However, the material does not routinely encourage students to pose such questions themselves.

The material provides some suggestions for how to avoid dogmatism. For example, the student text portrays the nature of science as a human enterprise in which students may participate (e.g., pp. 172-174s, Investigation: How Can I Learn More about That Property?). In addition, the material includes the work of particular, practicing scientists (e.g., pp. 185-188s, Reading: Elements of Explanations), and describes changes over time in scientific thinking about explanations of differing material characteristics (pp. 195-198s, Reading: Another Explanation).

The material provides a few examples of classroom interactions (e.g., dialogue boxes, vignettes, or video clips) that illustrate appropriate ways to respond to student questions or ideas, etc. Examples of desirable student-teacher dialogues are provided for discussions of the "bounceability" of balls (pp. 166-166at, Process and Procedure, part A) and the movement of food coloring in water (p. 203t, Process and Procedure, part A). Two sample student dialogues are provided for the development of scientific models of the particle model (pp. 232-233t, Students' Models). Some sense of other desirable student interactions may be gained from procedural directions and descriptions of student roles and social skills in cooperative group activities (e.g., pp. 192-194s, Investigation: Mystery Box).

The material provides some illustrations of the contributions of women and minorities to science and as role models. The illustrations sometimes occur in the main text (e.g., pp. 168s, 186-187s). They are also presented in sidebars that are interesting and informative, but may not be seen by students as central to the material (e.g., p. 166s, Sidelight on Technology). Children doing science in the video materials as well as cartoon characters of European scientists in the text are intended as role models for students. It is unclear, however, if students will relate to the cartoon animal figures, and their dialogues may appear extraneous to the main content of the text (e.g., p. 212s).

The material suggests multiple formats for students to express their ideas during instruction, including individual investigations and notebook writing (e.g., pp. 201-205s, Investigation: How Well Does the Particle Model Work?), cooperative group activities and lab investigations (e.g., pp. 183-185s, Investigation: Strange Phenomena, Part B-Puddle Mystery), and whole class discussion and drawing (e.g., p. 207bt, item 6). Introductory teacher's notes suggest using a wide variety of classroom activities for assessment, including in-class discussion, notebook entries, portfolios, and evaluate activities (Teacher's Resource Book, p. 33). However, the material does not usually provide a variety of alternatives for the same task in either instruction or assessment.

The material does not routinely include specific suggestions about how teachers can modify activities for students with special needs. However, the Teacher's Edition and Teacher's Resource Book provide some additional activities and resources for students. Within each chapter, the Teacher's Edition provides Further Opportunities for Learning, in which students may further study a related interest (e.g., p. 210t), sometimes using chapter and unit resources including websites (e.g., p. 179bt) and educational technology resources (software, CD-ROMs, videos, and laser discs [e.g., pp. 161b-161dt]). The Teacher's Resource Book includes a few extension activities similar in complexity to those in the student text (e.g., pp. 183-184).

The material provides a few strategies to validate students' relevant personal and social experiences with scientific ideas. A few text sections include a brief reference to a specific, personal experience students may have had that relates to the presented scientific concepts (e.g., p. 164s, Investigation: Bounce That Ball). In addition, a few tasks ask students about particular personal experiences they may have had or suggest specific experiences they could have. For example, after reading about the properties of translucence and hardness, students are asked to identify products in their homes with those properties (pp. 170-171s, Stop & Think, items 6, 9). However, the material rarely encourages students to contribute relevant experiences of their own choice to the science classroom, and sometimes it does not adequately link the specified personal experiences to the scientific ideas being studied (e.g., p. 171s, Stop & Think, items 11-12). Overall, support is brief and localized.

Endnote

Diversity and Limits describes its use of the five E's instructional model as follows: "Each chapter goes through a cycle of activities, and each activity exemplifies one of the "E" words. First the students are engaged by an event or question related to the concept that the teacher plans to introduce. Then the students participate in one or more activities to explore the concept. This exploration provides students with a common set of experiences from which they can initiate the development of their understanding of the concept. In the explain phase, the teacher clarifies the concept and defines relevant vocabulary terms. Next, the students elaborate and build on their understanding of the concept by applying it to new situations. Finally, the students complete an activity that will help them and the teacher evaluate their understanding of the concept" (level B, p. xvii).