Unlocking Learning Potential: The Science of Interleaved Practice

Interleaved practice is a powerful yet often overlooked learning strategy. A fascinating study involving college baseball players highlights its significance. In this experiment, players were divided into two groups, each exposed to 45 pitches during practice: 15 fastballs, 15 curveballs, and 15 change-ups. The key difference lay in the sequence of pitches.

One group practiced using “blocked practice,” encountering pitches in predictable blocks of 15—all fastballs, then all curveballs, followed by all change-ups. The second group experienced “interleaved practice,” where the pitches were mixed unpredictably. During a subsequent test, mimicking real game conditions, the interleaved practice group outperformed the blocked group significantly. This demonstrated how interleaved practice prepares learners to adapt to the unpredictable nature of real-world challenges.

Why Interleaved Practice Matters

Interleaving enhances learning by mimicking the decision-making processes required during testing or practical applications. Consider a typical mathematics scenario. Students often excel in practice but struggle during exams. Why? In practice, problems are usually blocked by type—e.g., a dozen questions on the Pythagorean theorem. Students only execute strategies rather than identify which strategy to use. On tests, however, problems are varied, requiring students to recognize the appropriate strategy before solving. Without interleaved practice, students lack the necessary experience to make these strategic decisions.

Real-World Classroom Evidence

Doug Rohrer, Robert Dedrick, and Kaleena Burgess conducted a robust classroom experiment with 7th-grade students over nine weeks (1). The goal: determine whether interleaving different types of math problems leads to better learning compared to blocking.

Experimental Design

Students practiced four types of math problems, with two types learned through blocked practice and two through interleaving. Blocking meant solving all 12 practice problems of a type within one assignment. Interleaving spread problems across multiple assignments, mixing them with other problem types. Importantly, the assignment of problem types to blocked or interleaved conditions was counterbalanced to eliminate biases.

Assessment and Results

Two weeks after the practice phase, students took a surprise test to ensure unbiased results. Interleaved practice led to nearly double the performance of blocked practice—72% accuracy compared to 38%. The findings underscored interleaving’s potential to promote durable, transferable learning.

Broader Implications

This principle extends beyond baseball and math. For example, learning to identify a kayak’s displacement across a lake using the Pythagorean theorem requires students to first recognize the problem type before solving it. Interleaved practice forces learners to practice both recognition and execution, fostering deeper understanding and adaptability.

Durability of Learning

Another experiment by Rohrer and colleagues further confirmed that interleaving improves long-term retention. Over 11 weeks, students in mixed conditions showed significant benefits, especially when tested after 30 days. Scores for interleaved practice were 74%, compared to 42% for blocked practice, demonstrating that the longer the interval, the greater the advantage of interleaving.

Conclusion

Interleaved practice trains learners for real-world complexity, improving not only immediate performance but also long-term retention. From baseball pitches to solving math problems, interleaving equips individuals to navigate unpredictability with confidence. The strategy’s enduring benefits make it a cornerstone for effective education.

References

1. Rohrer, D., Dedrick, R. F., & Burgess, K. (2014). The benefit of interleaved mathematics practice is not limited to superficially similar kinds of problems. Psychonomic Bulletin & Review, 21, 1323-1330. https://doi.org/10.3758/s13423-014-0588-3
2. Taylor, K., & Rohrer, D. (2010). The effect of interleaving practice. Applied Cognitive Psychology, 24, 837-848. https://doi.org/10.1002/acp.1598