We investigated whether and how prior knowledge activation improves learning outcomes for high school (less experienced learners) and university students (experienced learners) in a hypertext environment. Map coherence was defined as the extent to which relationships between the concepts in the map were made explicit. Therefore, we classified the mapping task of creating and labeling lines as low-coherent, and the mapping task of labeling provided lines as high-coherent. Learners were randomly assigned to the conditions of (1) high-coherent knowledge activation; (2) low-coherent knowledge activation; and (3) a baseline condition without prior knowledge activation. We found an overall effect for prior knowledge activation, learning experience, and an interaction between learning experience and the coherence of the prior knowledge activation task on learning outcomes. High school students benefited most from labeling provided lines, while university physics majors benefited most from creating and labeling lines. This interaction effect and effects of the specific mapping tasks on process measures support the claim that different prior knowledge activation tasks are suited for different groups of learners. (Contains 3 figures and 2 tables.)