There are three main types of evaluation: formative, summative, and diagnostic. Formative evaluation monitors student learning during instruction to provide feedback. Summative evaluation is given at the end of a course to determine if learning objectives were met and assign grades. Diagnostic evaluation is given before instruction to identify student strengths and weaknesses. Evaluations are also categorized based on whether student performance affects others' grades. Criterion-referenced tests measure individual performance against standards, while norm-referenced evaluations compare performance to peers on the same test. Placement evaluation determines student prerequisite skills and best learning approach.