The ongoing collection and documentation of evidence of students' performance in the classroom is a fundamental component of formative instructional practices, essential for ensuring student success. Multiple methods of collecting and documenting evidence of students' academic performance in the classroom are described. These methods include direct behavioral observations, evaluation rubrics, recording devices, general curriculum-based outcome measures, goal attainment scaling, and graphing performance. A discussion of how teachers can use data derived from these assessment methods to make instructional decision is provided.