Instructional systems differ in the amount of structure they impose on the 'educational environment' in which learning activities take place, e.g., mastery learning implies highly structured learning, whereas problem-based learning (PBL) claims its effectiveness just because of its 'freedom in learning'. Yet there seems to be a lot of structure in the educational system in which PBL is embedded. In this study dimensions of structure were explored in a curriculum based on PBL. Factor analysis on student judgments unfolded three forms of structure concerning different aspects of the educational environment: content, organization, and social setting. When looking for interactions between structure and student characteristics, e.g., in research on the effectiveness of PBL, it could be important to take this distinction in structure dimensions into account. In general, ATI-research suggests interaction effects for structure. The study that is presented here explored interactions between study orientation and students' appreciation of the three structure dimensions, revealing a rather consistent pattern of differences in appreciation tendencies influenced by the orientation of the student: meaning, dependence, minimalistic, or strategic. © 1991 Kluwer Academic Publishers.
