Introduction Th is second chapter of Part Two focuses on assessment, instruction, and learning in the classroom and on the beliefs, issues, and questions that are pertinent to this focus. Diagnostic teaching based on thoughtful teacher assessments and analyses is the recommended basis for classroom instruction. Th is diagnostic teaching and instruction is in response to, and part of, the formative qualitative assessments that teachers do every day. Qualitative assessment and instruction go hand in hand. As we observe and assess students’ skills and strategy use, we also consider, plan, and implement any needed instruction for them. In fact, assessment and instruction oft en overlap, and an outside observer might not be able to tell whether the teacher is assessing or instructing. Only the teacher knows whether his overall purpose is to assess, to instruct, or both, since many formative assessment techniques are also excellent teaching techniques, and vice versa.