The aim of this study is to investigate pre-service teacher's cognitive load types (intrinsic load-IL, extraneous load-EL, and germane load-GL), academic achievements, and affective characteristics (attitude and self-efficacy) at two stages of experimental learning processes. The first and the second groups used explanatory instructional multimedia science simulations (EImms-1 and EImms-2), and the third group used actual science laboratory experiments (ASLE). In the first stage, the pre-service teachers in the EImms-1 and 2 groups performed 20 different science experiments, and the students in the ASLE group performed the same experiments in the science laboratory. In the second stage, the groups were switched. The results show that the pre-service teachers in the EImms groups have significantly higher self-efficacy, more positive attitude, greater academic achievement, and lower IL, EL, and GL scores than those in the ASLE group. Also, the results are discussed with regard to cognitive load perspective.