There are several methods for assessing students' math skills, including formal and informal assessments. Formal assessments include achievement tests which measure overall math achievement and diagnostic tests which identify specific strengths and weaknesses. Informal assessments involve examining student work samples, using curriculum-based measurements, and teacher-constructed tests. Assessments should be given at the concrete, semiconcrete, and abstract levels to evaluate students' understanding. Periodic and continuous assessments are also important to monitor progress.