Do student-generated rational sets of examples facilitate concept acquisition?

The effects of type of individual generating study examples (teacher vs. student) and type of examples generated (rational set vs. nonrational set) on coordinate concept acquisition were investigated in a 2 × 2 analysis of covariance design. The main effects and the interaction effect for the posttest measure of concept acquisition were not statistically significant. However, pairwise comparisons revealed that the posttest scores were significantly lower (p <.05) for the group hypothesized to learn best, namely, students who created their own examples using the rational set generator. Several possible explanations for these results, including the compatibility of the rational set generator with all coordinate concept groups and time needed by students to use the generator appropriately, are discussed.