Learning rates and known-to-unknown flash-card ratios: comparing effectiveness while holding instructional time constant.

Using alternating treatments designs, we compared learning rates across 2 computer-based flash-card interventions (3 min each): a traditional drill intervention with 15 unknown words and an interspersal intervention with 12 known words and 3 unknown words. Each student acquired more words under the traditional drill intervention. Discussion focuses on the need to account for instructional time when learning procedures are evaluated and compared.