Use these targeted probes to assess students’ grasp of key mathematical concepts! This resource provides secondary teachers with assessment tools to gauge learners’ knowledge of core mathematical ideas. The authors provide 30 probes - brief, easily administered assessments - that can determine students’ thinking by revealing common understandings and misunderstandings and providing further elaboration of student thinking. This invaluable book: combines standards, educational research findings, and practical craft knowledge; helps teachers modify math instruction to build on individual students’ existing understandings while addressing their identified difficulties; and, offers examples that illustrate the faulty thinking students are likely to exhibit and typical obstacles they may encounter.