on the review teams. Published science instructional materials are not always scientifically sound or up to date. Moreover, some materials do not consistently reflect an understanding of what is and what is not important in a particular scientific discipline. The Committee found, in its examination of instructional materials, many cases where materials contained detailed information of little relevance, extensive unnecessary vocabulary, and only cursory treatment of the essential concepts. Scientists on the review team are helpful in judging the accuracy of the science presented in the material and the importance of the information for understanding essential concepts.
6. An evaluation instrument needs to serve diverse communities, each one of which has its own needs. Since an evaluation instrument for instructional materials will be used by different groups for a variety of purposes, no single model can be assumed. In most cases, school district evaluation groups will use it; however, individual schools and statewide evaluation groups will also use the tool. These evaluation groups will have varying resources, and the students being taught will differ with respect to language proficiencies, economic status, abilities and disabilities, and home support resources. Therefore, the Committee resolved to design a tool that is adaptable.
7. Tension exists between the need for well-informed, in-depth analyses of instructional materials and the real limitations of time and other resources. The National Science Teachers Association surveyed some 10% of its members just before the release of the Standards, in January 1996, to ascertain their perceptions of the barriers to implementation of these national standards (Wheeler, 1999a). Two major impediments were identified: lack of time and lack of other resources. The Committee resolved to develop a tool that recognizes the real limitations faced by the evaluators of instructional materials.
8. Many evaluators (including teachers, administrators, parents, and scientists) using the tool will be unfamiliar with current research on learning. Curriculum decisions are not always informed by research on learning, but rather on what feels comfortable to teachers, what seems to work, or what is expected (Orpwood, 1998). Once teachers have completed their formal education and begun to teach in the classroom, access to research publications and the time to review them are a challenge. Most scientists also lack the time and interest to delve deeply into education research. In addition, the typical professional development workshops for teachers rarely devote time to in-depth study of