of science content. TIMSS found that grade 8 textbooks in the United States covered 65 science topics compared with about 25 topics typical of other TIMSS countries. The authors note that (Valverde and Schmidt, 1997, p. 3): “U.S. eighth-grade science textbooks were 700 or more pages long, hardbound, and resembled encyclopedia volumes. By contrast, many other countries’ textbooks were paperbacks with less than 200 pages.”
Another study, focusing on high school biology texts, indicated that the most widely used texts provided little support for student learning through laboratory experiences. AAAS developed and applied a detailed protocol to 10 widely used biology curricula, including 4 developed with NSF support. AAAS found that all of these curricula (which included kits of laboratory materials) did a poor job in terms of two criteria that might reflect laboratory experiences: (1) engaging students with relevant phenomena and (2) helping them to develop and use scientific ideas (American Association for the Advancement of Science, 2000).
A panel convened by NSF to review its middle school science curricula gave the texts generally high marks (3 or higher on a 5-point scale) and found that they were consistent with the NSES. However, the panel noted a lack of attention to one of the goals of laboratory experiences—enhanced understanding of the nature of science—in these curricula (National Science Foundation, 1997). In a subsequent review of a sample of NSF-funded curricula for elementary, middle, and secondary mathematics and science, experts gave the science curricula high marks (on a 1 to 5 scale) on several criteria that reflect the goals of laboratory experiences, including:
Do the materials provide sufficient activities for students to develop a good understanding of key science concepts? 4.5
Do the materials accurately represent views of science as inquiry? 4.4
To what extent do the materials provide students the opportunity to make conjectures, gather evidence, and develop arguments to support, reject, and revise their preconceptions and explanations? 4.3
In this evaluation, the panel found that, although the content of the curriculum materials (including laboratory kits) was generally high, dissemination was limited. Often, curriculum materials were adopted by a single teacher, rather than a school or a school district. Most large textbook publishers chose not to develop commercial versions of NSF-funded materials (Tushnet et al., 2000). The panel also found that teachers and administrators were unaware of the full range of materials available, and teachers were often unprepared for the changes in instructional strategy required to successfully implement the curricula.
In conclusion, curriculum materials appear to influence science teachers’ teaching strategies, including decisions about when and how to engage