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Abstract
Multimedia instructional materials were used to design science presentations for the topics of Magnetism and Light. Two experiments 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 for younger students with no prior knowledge of the topic, an audio-visual presentation was superior to an auditory presentation only. These students required a visual presentation to make sense of the auditory explanation. However, 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. Together, these two sets of results provide an example of the expertise reversal effect that can be explained by cognitive load theory. These results also provided a basis from which an hypothesis was generated to determine the effectiveness of hands-on instructional materials in science. Experiment 3 was conducted with younger learners (Years 5 and 6) who had no prior knowledge of Newton s First Law of Motion. Half of the learners were presented the information explicitly by the teacher who used instructional materials to visually demonstrate the explanations. The other half watched this presentation while also using the instructional materials themselves during the presentation. Results indicated that if the students are presented with a redundant set of representations, these materials may have a negative consequence for the learning process. Experiment 4 replicated Experiment 3 with minor changes to the experimental design to eliminate possible threats to the validity. The results obtained were similar to those of Experiment 3. The cognitive processing associated with hands-on materials by the students may impose an excessive working memory load. These results provided additional support to those generated by Experiments 1 and 2, emphasising the importance instructors should place on the identification and consideration of prior learning before designing instructional materials.