This book presents teacher-written cases relating stories, insights, and experiences about the teaching of fractions, decimals, ratios, and percents. The cases were written to stimulate colleagues to examine their own practice, to think hard about the mathematics they teach and would like to teach, and to initiate inquiries and discussions that lead teachers to a deeper understanding of student thinking and the kinds of strategies that would promote further learning. The typical case reports a problem, dilemma, or crisis of mathematics instruction that has occurred in a teacher's class and describes the events that led up to the problem, the classroom context in which it occurred, and the ways in which the teacher attempted to set matters on course. Also included is the teacher's own analysis of the situation and the emotional impact of the problem. Major section headings in the book are: "Inside Student Thoughts,""Making Sense or Memorizing Rules,""Teaching as Questioning,""Reflecting,""Manipulatives Aren't Magic,""What Next," Connections," and "This Wasn't My Plan." Contains 38 references. (MKR)