Experimental evaluation of classroom environments: scheduling planned activities.

Scheduling of planned activities in a classroom for TMR adolescents was investigated. Ten classroom activities were scheduled in either a predictable (fixed) or unpredictable (random) order using an ABAB design. Relative to fixed scheduling, random scheduling resulted in significantly lower rates of activity completion and higher rates of disruptions. Lower rates of task completion also generalized to two unmanipulated activities. Activity completion and rate of disruptions, while generally inversely related, were significantly correlated for only 2 of 11 students. Students with lower levels of task completion under fixed scheduling showed the largest decrements in performance under random scheduling. Higher rates of disruptions under fixed scheduling were also associated with greater increments in disruptive behavior under random-scheduling conditions. Factors relating to the generality of these findings were discussed.