Cognitive load theory (Sweller, 1988) “is concerned with the development of instructional methods that efficiently use people’s limited cognitive processing capacity to stimulate their ability to apply acquired knowledge and skills to new situations (CLT; Paas, Tuovinen, Tabbers & Van Gerven, 2003, p. 63).” The major assumption behind the CLT is that individual’s working memory has limited capacity (Kirschner, 2002: Paas, Tuovinen, Tabbers & Van Gerven, 2003) and the effectiveness of instructional design depends on that central constraint (Sweller, Merrienboer&Paas, 1998, Schnotz & Kürschner, 2007).In the context of CLT, the efficiency of instructional condition computed with test performance and invested mental effort to attain this performance was introduced by Paas and Van Marrienboer (1993). Rather than comparing performance on a task or test, it is important to evaluate invested mental effort to attain this performance. By doing so, the instructional designers are able to compare the efficiency of instructional conditions. It is assumed that measuring transfer performance gives information about the effectiveness of instructional condition; however, combining performance with mental effort can provide information about the efficiency of instructional condition (Paas & Van Marrienboer, 1993).Although the original construct for instructional efficiency conceptualized as presented above, it is revealed that many researchers use an adapted version of this efficiency measure (Van Gog & Paas, 2008). Among 37 studies used instructional efficiency measure since 1993, it is found that 33 studies used the adapted version of instructional efficiency measure. The original instructional efficiency measure tries to find out the learning outcome as a combination of performance and invested mental effort to attain the performance, the adapted measure tries to represent the instructional efficiency in terms of the learning process in that the invested mental effort in instruction and test performance after instruction has been combined in equation for instructional efficiency. Adaptive instructional efficiency measure has been conducted in two ways. Mental effort invested in learning phase combined with performance in learning (Corbalan, Kester, & Van Merriënboer, 2006; Salden, Paas, & Van Merriënboer, 2006) and the mental effort combined with test score to calculate the instructional efficiency (Tindall-Ford, Chandler, & Sweller, 1997). Van Gog and Paas (2008) point out that using adaptive measure of instructional efficiency might show interesting result if the aim of the study is to manage the extraneous cognitive load in instruction. However, it is assumed that using adaptive measure for studies aims to increase germane cognitive load is misleading.Therefore the following research questions were guided this current study,

• Is there a significant difference between the first and second version of multimedia in adaptive instructional efficiency (learning phase) for mitosis?
• Is there a significant difference between the first and second version of multimedia in adaptive instructional efficiency (test phase) for mitosis?
• Is there a significant difference between the first and second version of multimedia in adaptive instructional efficiency (learning phase) for meiosis?
• Is there a significant difference between the first and second version of multimedia in adaptive instructional efficiency (test phase) for meiosis?

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