We chose a framework that requires that evaluations should meet the high standards of scientific research and be fully dedicated to serving the information needs of program decision makers (Campbell, 1969; Cronbach, 1982; Rossi et al., 1999). In drawing conclusions on the quality of the corpus of evaluations, we demanded a high level of scientific “validity” and “credibility” because of the importance of this report to national considerations of policy. We further acknowledge other purposes for evaluation, including program improvement, accountability, cost-effectiveness, and public relations, but do not address these purposes within our defined scope of work. Furthermore, we recognize that at the local level, decisions are often made by weighing the “best available evidence” and considering the likelihood of producing positive outcomes in the particulars of context, time pressures, economic feasibility, and resources. For such purposes, some of the reported studies may be of sufficient applicability. Later in this section, we discuss these issues of utility and feasibility further and suggest ways to maintain adequate scientific quality while addressing them.

Before discussing the framework, we define the terms used in the study. There is ambiguity in the use of the term “curriculum” in the field (National Research Council [NRC], 1999a). In many school systems, “curriculum” is used to refer to a set of state or district standards that broadly outline expectations for the mathematical content topics to be covered at each grade level. In contrast, at the classroom level, teachers may select curricular programs and materials from a variety of sources that address these topics and call the result the curriculum. When a publisher or a government organization supports the development of a set of materials, they often use the term “curriculum” to refer to the physical set of materials developed across grade levels. Finally, the mathematics education community often finds it useful to distinguish among the intended curriculum, the enacted curriculum, and the achieved curriculum (McKnight et al., 1987). Furthermore, in the curriculum evaluation literature, some authors take the curriculum to be the physical materials and others take it to be the physical materials together with the professional development needed to teach the materials in the manner in which the author intended. Thus “curriculum” is used in multiple ways by different audiences.

We use the term “curriculum” or “curricular materials” in this report as follows:

A curriculum consists of a set of materials for use at each grade level, a set of teacher guides, and accompanying classroom assessments. It may include a listing of prescribed or preferred classroom manipulatives or technologies, materials for parents, homework booklets, and so forth. The curricula reviewed in this report are



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