An attempt was made to increase Swedish preschool children's understanding of aspects of commercial enterprise, particularly those of "the shop," by introducing a specific didactic approach to preschool education. Of particular interest were two aspects of the shop: advertising and the principle of trade. A total of 77 children up to 7 years of age worked in 4 groups for 2 to 3 weeks on the theme of "the shop." Groups A and B were instructed in line with the assumptions that: (1) if the teacher knows how children think about the content to be taught, it should be easier for the teacher to develop the children's understanding; (2) student reflection on teacher-made situations and problems leads to understanding; and (3) children would have to reflect on content, structure, and their learning if the approach were to succeed. Teachers of groups A and B planned and used situations, problems, and questions which were supposed to increase their students' understanding. Comparison groups C and D worked out the instructional theme individually. In a manner similar to that of the Piagetian clinical interview, children were interviewed three times about the shop theme. Findings, which favored the didactic approach, indicated that comparison and treatment groups differed markedly in their understanding of advertising and the function of money in the shop. (RH)