We investigated the effects of rapid assessment tasks and different adaptive restudy prompts in multimedia learning. The adaptivity was based on rapid assessment tasks that were interspersed throughout a multimedia learning environment. In Experiment 1 (N = 52 university students), we analyzed to which extent rapid assessment tasks were reactive (i.e., whether these tasks change what should be measured) and, thus, had per se positive effects on learning. In Experiment 2 (N = 41 university students), we analyzed the advantages and disadvantages of specific and unspecific restudy prompts (i.e., focus on a very specific piece of knowledge or on the corresponding knowledge sub-area). We found no reactivity associated with the assessment tasks. Most specific knowledge gaps could be closed by either type of prompt. However, unspecific prompts fostered the overall learning outcomes more than specific prompts. The present adaptation procedure is a good starting point for developing powerful adaptation mechanisms.