Brooks (1999) compared algebra achievement of students enrolled in the intervention group (I CAN Learn[R] classes) to that of students enrolled in the comparison group (traditional classes) at pretest, midyear, and posttest. Brooks found that students in the I CAN Learn[R] classes achieved higher scores in algebra than students in traditional classes at both midyear and posttest, and the difference was statistically significant. The results should be viewed with caution because the unit of analysis (student) does not match the unit of assignment (classrooms).