Interleaved Practice Improves Mathematics Learning created by Doug Rohrer, Robert F. Dedrick, and Sandra Stershic

A typical mathematics assignment consists primarily of practice problems requiring the strategy introduced in the immediately preceding lesson (e.g., a dozen problems that are solved by using the
Pythagorean theorem). This means that students know which strategy is needed to solve each problem
before they read the problem. In an alternative approach known as interleaved practice, problems from
the course are rearranged so that a portion of each assignment includes different kinds of problems in an
interleaved order. Interleaved practice requires students to choose a strategy on the basis of the problem
itself, as they must do when they encounter a problem during a comprehensive examination or subsequent
course. In the experiment reported here, 126 seventh-grade students received the same practice problems
over a 3-month period, but the problems were arranged so that skills were learned by interleaved practice
or by the usual blocked approach. The practice phase concluded with a review session, followed 1 or 30
days later by an unannounced test. Compared with blocked practice, interleaved practice produced higher
scores on both the immediate and delayed tests (Cohen’s ds 0.42 and 0.79, respectively).