Instructional task variables of analytical explanation and sequence were studied in two experiments to assess the systems approach proposition of efficiency and effectiveness in concept learning. The independent variable of analytical explanation consisted of two components: a procedure for focusing the subject's attention on the critical attributes of the given concept, and a presentation of the strategy used to determine classification of the examples. Sequence of instances involved an organized presentation based upon the relationship of the stimulus attributes. Subjects in both experiments were college students. Organized and analytical explanation treatments resulted in less time to complete the training program, fewer errors, and less time on the posttest than the random and no analytical explanation treatments. (Author)