A project designed to examine the effects of maximizing time on computer and computer-to-pupil ratio was implemented in an urban middle school in the Southwest. A sixth grade classroom was equipped with enough microcomputers for a 1:1 computer-to-pupil ratio. Students in two mathematics classes received instruction almost entirely on computer for the duration of the school year. Two control classes received a teacher-directed, group-centered instructional mode from the same teacher. Data were collected which examined the impact of CAI on mathematics achievement, student attitude, attendance, and discipline. Results indicated that immersion in CAI did have a significant effect on mathematics achievement. Discriminant function analysis yielded a significant function comprised of three variables: number of times tardy, number of discipline cards, and math computation raw score. The magnitude of these differences, however, was not great; 1.9 items in math computation raw score and one time tardy to math class. These results emphasized the difference between practical and statistical significance, both of which must be weighed in evaluation research.