The current study examined the effects of computer-based self-explanations (i.e., generated by the learner) and instructional explanations (i.e., provided to the learner) on undergraduate biology students’ revision of photosynthesis and respiration misconceptions. Individual differences, particularly students’ prior knowledge, significantly impact the effectiveness of instructional tasks. Oftentimes, an instructional task is effective only for learners at a particular prior knowledge level. Cognitive Load Theory suggests that too much or too little instructional support can overwhelm a learner’s working memory. When used for building knowledge, self-explanations and instructional explanations, like those employed in the current study, both interact with prior knowledge. Prior research has indicated that instructional explanations may only benefit students with low prior knowledge, and self-explanations may only benefit students with high prior knowledge. The current study addressed whether such effects extend to the use of explanation tasks to facilitate knowledge revision, in which existing misconceptions are revised. Four hundred and thirty eight undergraduate major and non-major biology students completed an online activity for course credit. Participants were randomly assigned to one of three conditions (self-explanation, instructional explanation, or no explanation) and then prompted with a set of photosynthesis questions, each of which was followed by their assigned instructional task and a cognitive load measure. One week later, participants returned to the activity to take a posttest. Results indicated students entered the activity with high rates of photosynthesis and respiration misconceptions. Further regression analyses indicated that only self-explanations, not instructional explanations, increased learning compared to no explanations. Trends in effect sizes suggest self-explanations only benefited students with sufficient prior knowledge. Higher cognitive load was associated with less learning in both explanation conditions, but not in the no explanation condition. The current results suggest that self-explanations may effectively promote knowledge revision, assuming students are familiar with the content, while instructional explanations may not foster knowledge revision in a computer-based setting. Implications for adaptive instruction that targets knowledge revision are addressed
