Table 2.

Number of Classes in Both Curriculum Conditions

Test	Treatment			Control
	Grade 3	Grade 4	Grade 5	Grade 3	Grade 4	Grade 5
Cardiovascular fitness	30	33	39	42	41	40
Muscular fitness	31	34	36	38	38	42
Flexibility/nutrition	28	31	33	40	37	42

Note.—The differences in the numbers of classes were due to attrition. We recorded a 20% attrition rate. Over the course of the study, some schools had to increase or reduce classes during the semester to accommodate enrollment change. The number of classes might increase when overcrowded classes were split into smaller classes; the number might decrease when most students in one class left for other schools and the remaining students were combined with other classes.