Two experiments using the science topics of Magnetism and Light were conducted with younger learners (Year 5) who had no prior knowledge of the topics, and older learners (Year 6) who had studied the topics previously. Half of the learners were presented the information in auditory form only while the other half were presented the auditory information simultaneously with a visual presentation. Results indicated that older students with prior knowledge of the topic learned more from the auditory only presentation. For these students, the addition of visual information was redundant and so they were disadvantaged by the use of an audio-visual presentation. However, for younger students with no prior knowledge of the topic, the difference between means reversed. Some of these students might require a visual presentation to make sense of the auditory explanation. These two sets of results were discussed in the context of the redundancy and the expertise reversal effect.