The results of a randomized controlled trial, published in Journal of Educational Psychology, suggest that a greater emphasis on interleaved practice may dramatically improve math test scores for seventh graders. Whereas most mathematics worksheets consist of a block of problems devoted to the same skill or concept, an interleaved worksheet is arranged so that no two consecutive problems require the same strategy.

Doug Rohrer and colleagues conducted the study with 54 classes in a large school district in Florida during the 2017–2018 school year. Over a period of four months, the classes periodically completed either interleaved or blocked worksheets, and then both groups completed an interleaved review worksheet. All students completed the same problems. One month later, students took an unannounced test which was set by the researchers. The study found that:

• Students who had completed the interleaved assignments performed much better on the unannounced test than those in the blocked assignment group (effect size = +0.83).
• Majority of the teachers reported that they like interleaved practice and would be able to use it with no or little instruction.
• However, most teachers also considered interleaved practices would be more time-consuming than blocked practices.

The researchers suggest that the large effect sizes observed in the study for interleaved math practice may be due to the learning strategies it involves, which force the student to choose an appropriate strategy for each problem on the basis of the problem itself. They also identified some limitations of the study – particularly that the interleaving students took longer to complete their worksheets so effectively spent more time on each topic.

Source : Rohrer, D., Dedrick, R. F., Hartwig, M. K., & Cheung, C.-N. (2019). A randomized controlled trial of interleaved mathematics practice. Journal of Educational Psychology. Advance online publication. doi: 10.1037/edu0000367