The Effects of Explicit Timing on Math Performance1

Many elementary school teachers rely on the clock to start and stop academic assignments, thus periods, or portions of periods, are usually allotted for com- pletion of a set amount of work. This contingency is much like a fixed-interval schedule of reinforcement, in which the child has a fixed amount of time either to finish an assignment or complete as much work as possible. Although such timing is present in most classrooms, children are rarely aware of it, and teach- ers often extend or reduce the length of an activity period as a function of student performance.