This document was prepared to assist teachers in Virginia in three ways: (1) by assessing student achievement on the competencies adopted by the State Board of Education; (2) by diagnosing student errors in mathematics; and (3) by prescribing instructional activities designed to promote student mastery of skills assessed in the competency program. The materials should prove helpful in strengthening the instructional program and in developing high quality criterion-referenced tests. Following a list of some steps which should be considered in planning a minimum competency program, the first section considers ideas on test construction and assessment. In addition to some test-construction suggestions, sample test items and suggestions for generating questions and answer choices are given by performance indicator. The second section considers instructional suggestions and activities for the skill associated with each performance indicator. Common errors are listed, but the majority of the material presents activities which the classroom teacher would find useful in teaching or reteaching the skill. Appendices present the state adopted competencies for mathematics, vocabulary, and a brief description of the Graduation Competency Test in mathematics. (MNS)