Depletion of limited working memory resources may occur following extensive mental effort resulting in decreased performance compared to conditions requiring less extensive mental effort. This 'depletion effect' can be incorporated into cognitive load theory that is concerned with using the properties of human cognitive architecture, especially working memory, when designing instruction. Two experiments were carried out on the spacing effect that occurs when learning that is spaced by temporal gaps between learning episodes is superior to identical, massed learning with no gaps between learning episodes. Using primary school students learning mathematics, it was found that students obtained lower scores on a working memory capacity test (Experiments 1 and 2) and higher ratings of cognitive load (Experiment 2) after massed than after spaced practice. The reduction in working memory capacity may be attributed to working memory resource depletion following the relatively prolonged mental effort associated with massed compared to spaced practice. An expansion of cognitive load theory to incorporate working memory resource depletion along with instructional design implications, including the spacing effect, is discussed.

I always believe that if I set up a big goal, I may reach a smaller one; if I set up a small goal, I may get nothing. Therefore, when I was in my master degree, I determined to do a PhD after that.A three-year PhD is really not long enough. Although I did almost the same thing every day, I still felt very happy and satisfied. I believe that I owe my satisfaction to my two helpful and supportive supervisors, Professor Slava Kalyuga and Emeritus Professor John Sweller.On the one hand, my principal supervisor, Professor Slava Kalyuga, gave me a lot of guidance on how to improve my academic writing and English grammar. Because of Slava's comments on my academic writing, I was able to finish my dissertation in time; on the other hand, my second supervisor, Emeritus Professor John Sweller, instructed me how to design experiments and how to analyze data from different aspects. Because of my two supervisors' cooperation, I successfully published two papers and another three papers are being under review during my PhD study, which I hope will make my research internationally recognized.The second thanks should go to the China Scholarship Council which provided me with a research grant to do my PhD at UNSW. Without their help, I could not pursue my PhD overseas and fulfill my goals.The last but very important thanks is to my parents who supported my continued study and research. As an international student, I have left home for a long time and missed a lot of chances to hug and kiss my dearest parents, so I must say that I cannot be a Doctor without their support.

Within the framework of cognitive load theory, the element interactivity and the expertise reversal effects usually are not treated as closely related effects. We argue that the two effects may be intertwined with the expertise reversal effect constituting a particular example of the element interactivity effect. Specifically, the element interactivity effect relies on changes in element interactivity due to changes in the type of material being learned while the expertise reversal effect also relies on changes in relative levels of element interactivity but in this case, due to changes in relative levels of expertise. If so, both effects rely on equivalent changes in element interactivity with the changes induced by different factors. Empirical evidence is used to support this contention.

The contradiction between the worked example effect that occurs when learners presented with more instructional guidance learn more than learners presented with less guidance and the generation effect that occurs when the reverse result is obtained can be resolved by the suggestion that the worked example effect is obtained using materials high in element interactivity, whereas simpler, low element interactivity materials result in the generation effect. A 2 (guidance: low vs. high) x 2 (element interactivity: low vs. high) x 2 (expertise: low vs. high) experiment investigated this hypothesis with high school trigonometry learners. On an immediate test, high guidance reflecting a worked example effect was found for novices, but a generation effect was obtained for more knowledgeable learners. In contrast, on a delayed test, a three-way interaction between guidance, element interactivity and expertise was found. This interaction was caused by a worked example effect for material high in element interactivity and a generation effect for material low in element interactivity for novices while for more knowledgeable learners, a generation effect was obtained for both low and high element interactivity materials. These results suggest firstly, that both the worked example and generation effects may be more likely on delayed than immediate tests and secondly, that the worked example effect relies on high element interactivity material while the generation effect relies on low element interactivity material.