A unit on animals was taught to 64 preschool children (44 in an experimental group and 20 in a control group). Children in the experimental group were taught nine major concepts over four levels of abstraction (designated as superordinate, intermediate, subordinate, or particular levels). Each concept was presented by means of an advance organizer followed by related activities. The order of presentation was sequenced in a hierarchical manner with superordinate concepts being taught first and particular concepts being taught last. Animal concepts were also taught to the control group, but advance organizers were not employed and concepts were introduced primarily at the particular level. Over a 10-week period, five concept tests were administered to all 64 children. Tests were composed of four subtests designed to measure concept attainment at four levels of generality. Results indicated that children in the experimental group, as compared to those in the control group, obtained significantly higher performance scores on 14 out of 15 subtests and showed significant score increases from the first to the fifth test on all four levels of concept generality. (Author/MP)