Summary of“Interleaving Retrieval Practice Promotes Science Learning” by Faria Sana and Veronica X. Yan (2022) Main Question
The study investigated whether interleaving quiz questions from different science concepts, rather than grouping questions by topic, improves long-term learning in high school science classes.
Key Learning Principles
The researchers combined two well-established learning strategies:
Retrieval practice: Actively recalling information through quizzes or testing strengthens learning and memory.
Interleaving: Mixing questions from different concepts instead of practicing one concept at a time helps students distinguish between concepts and apply them more effectively.
Study Design 155 students in Grades 9-12 science courses participated. Over 4 weeks, students took brief weekly quizzes. Some quiz questions were: Blocked: questions on the same concept appeared together.
Interleaved: questions on different concepts were mixed. A surprise final test was given one month later.
Major Findings 1. Quizzing improved learning
Students scored better on concepts that had been quizzed than on concepts that had not been quizzed:
Quizzed (blocked): 54% Not quizzed (control): 47%
This replicates the well-known retrieval practice effect.
- Interleaving worked even better
Students performed best on concepts practiced through interleaved quizzes:
Control: 47% Blocked quizzes: 54% Interleaved quizzes: 63%
Thus, interleaving provided additional benefits beyond quizzing alone.
- Harder practice produced better learning
Students actually scored lower on the interleaved quizzes themselves than on blocked quizzes, indicating that interleaved practice felt more difficult. However, it led to superior long-term retention on the final test.
Why Interleaving Helps
The authors argue that interleaving encourages students to:
Compare similar concepts. Notice critical differences between ideas. Develop deeper conceptual understanding rather than relying on memorization.
For example, students learn not only what a concept is, but also how it differs from related concepts and when to apply it.
Educational Implications
The intervention was remarkably simple:
Weekly quizzes lasted only 10-12 minutes. No special teacher training was required. The approach cost little and fit easily into existing classes.
The authors suggest that teachers can improve learning by:
Replacing some long exams with frequent low-stakes quizzes. Mixing topics within quizzes instead of grouping questions by topic.