The study aims to identify the effect of a flipped classroom approach designed according to the cognitive theory of multimedia learning on the academic achievements of eighth‐grade students (aged 14 years) in Saudi Arabia in computer science. To this end, a quasi‐experimental design was used, with a sample of 67 students; 33 students were assigned to the experimental group, whereas 34 comprised the control group. The experimental group was subjected to the flipped classroom approach, whereas the control group was given direct instruction. To measure student achievements, an instrument that measures cognitive skills based on Revised Bloom's taxonomy levels was designed. Findings revealed a positive effect on the experimental group's achievement levels with respect to Bloom's higher order thinking skills, that is, applying, analysing, and evaluating. No difference was found between the two groups in terms of academic achievements at the remembering and understanding levels of Bloom's taxonomy. Moreover, learners with low prior knowledge showed a higher improvement in academic achievements compared with those with high prior knowledge. This corresponds to the assumption of the cognitive theory of multimedia learning that learners with low prior knowledge would benefit from its principles more than learners with high prior knowledge.