This book of case studies came from the final year of a three-year research collaboration among a team of teachers and project staff entitled What Influences Teachers’ Modifications of Curriculum? (National Science Foundation ESI 0455711). The case study, in this chapter, is of student thinking in one teacher’s classroom. The teacher is a “ringer,” a highly experienced teacher with an unusual set of qualifications—including certification in special education, social studies, and science, and experience working in an alternative program for students with substance abuse problems. So she’s a little different from the teachers in other cases in this book. The authors include this case to have an example of work in special education: This teacher was a “self-contained” class for students with a wide range of diagnosed special needs. This sample chapter also includes the Table of Contents and Index.