The purpose of this study was to conduct a formative evaluation of computer assisted instruction materials for high school mathematics. The materials chosen were produced for Alberta Education to teach Mathematics 30 using computer assisted instruction (CAI). Subjects included the students enrolled in Mathematics 30 in two high schools in a county in Alberta. Entry level mathematics skills of both groups of students were assessed using a pretest. The first group of students used the CAI materials to learn the concepts in Mathematics 30. Based on feedback from this first group the CAI materials were modified. A second group used these modified CAI materials. Both groups completed the same paper and pencil mathematics posttest after completing the lessons. The mean length of time students took to complete each topic in the unit was reported. The study was mainly descriptive and involved informal interviews with the students and mathematics teachers who used the materials. The purpose of these interviews was to determine their opinions about the CAI materials and CAIas a method of learning mathematics. The results of these interviews were summarized into a number of statements about the materials and students' and teachers' perceptions of their use.