Two experiments are reported that investigated the relative effectiveness of a realistic dynamic visualization as opposed to a schematic visualization for learning about cell replication (mitosis). In Experiment 1, 37 university students watched either realistic or schematic visualizations. Students' subjective task demands ratings as well as their performance in a multiple-choice test and a pictorial test clearly demonstrated the superiority of the schematic dynamic visualization. In Experiment 2, 83 students were given the two visualizations in four different orders of presentation. Students showed the same performance irrespective of whether they watched the schematic visualization twice, first saw the schematic and then the realistic visualization or vice versa. Only students, who watched the realistic visualization twice, had far lower learning outcomes. Contrary to our expectations, for both experiments, students' prior knowledge did not moderate the results. (Contains 3 tables and 2 figures.)