Can interleaved retrieval practice enhance learning in classrooms? Across a 4-week period, ninth- through 12th-grade students (N = 155) took a weekly quiz in their science courses that tested half of the concepts taught that week. Questions on each quiz were either blocked by concept or interleaved with different concepts. A month after the final quiz, students were tested on the concepts covered in the 4-week period. Replicating the retrieval-practice effect, results showed that participants performed better on concepts that had been on blocked quizzes (M = 54%, SD = 28%) than on concepts that had not been quizzed (M = 47%, SD = 20%; d = 0.30). Interleaved quizzes led to even greater benefits: Participants performed better on concepts that had been on interleaved quizzes (M = 63%, SD = 26%) than on concepts that had been on blocked quizzes (d = 0.35). These results demonstrate a cost-effective strategy to promote classroom learning.
Keywords: classroom learning; interleaving; open data; open materials; retrieval practice.