sharply among schools. Simply put, the standards are higher in schools with more affluent students. As Puma et. al. (1997) found in their extensive study of the program (then Chapter 1), an A in a high-poverty school was the equivalent of a C in a low-poverty school.

Standards are intended to change that practice by setting out a body of knowledge and skills that are essential for all students to learn and expecting all students to learn it. The explicit intention of the reformers was to set challenging standards for all students.

Research on standards and standards-based systems specifies two types of standards: content standards and performance standards. Both are required by the Title I statute.

Content standards spell out what students should know and be able to do in core subjects. They indicate, for example, the topics and skills that should be taught at various grade levels or grade spans. At the national level, the mathematics standards developed by the National Council of Teachers of Mathematics and the science standards developed by the National Research Council (NRC) are examples of content standards. For example, the NRC's National Science Education Standards for physical science state that, at grades K-4, “all students should develop an understanding of properties of objects and materials; position and motion of objects; [and] light, heat, electricity, and magnetism.” In grades 5–8, “all students should develop an understanding of properties and changes of properties in matter; motions and forces; [and] transfer of energy.” In grades 9–12, “all students should develop an understanding of structure of atoms; structure and properties of matter; chemical reactions; motions and forces; conservation of energy and increase in disorder; [and] interactions of energy and matter” (National Research Council, 1996:123, 149, 176).

In addition to the standards proposed by national groups, nearly all states have developed content standards in core subjects. These standards vary widely, however. Some states set standards for grade clusters, like the National Science Education Standards, while others set standards for each grade. Some focus on a few big ideas, while others are quite extensive.

The purpose of content standards is to guide instruction by providing a common focus for policy and practice (Ravitch, 1995). At the policy level, they provide guidelines for the development of assessments, instructional materials, and professional development opportunities, thus helping to steer teachers' decisions about what to teach. In addition, the standards documents themselves set common expectations for all classrooms and provide a yardstick for school