Research into Learning Hierarchies

Learning hierarchy research began with a small preliminary study by Gagne (1962), in which he attempted to teach seven children how to find formulas for sums of terms in number series. Gagne suggested that this skill could not be acquired unless the learners possessed certain prerequisite skills, which were identified by asking what would the individual have to be able to do in order that he can attain successful performance on this task, provided he is given only instructions? [p. 358]. The same question was then applied to each of the prerequisite skills, thus identifying more skills; the process was continued until very basic skills were reached. In this way Gagn6 derived a network of elements which he called a hierarchy of knowledge. He taught the skills to the seven children, and observed that none of them acquired a skill without also acquiring all of the skills that were shown as subordinate to it in the hierarchy. This result suggested that, if hierarchies were generally valid representations of the sequences in which skills or elements of knowledge must be learned, then they would be valuable tools for shaping more effective instruction for the acquisition of problem-solving skills and knowledge in general. Despite this important implication, few investigations of the validity of hierarchies were performed in the subsequent decade, and these were almost totally restricted to subject matter in mathematics and science, and generally ended in inconclusive results. Causes of the inconclusive results need to be identified to improve future research.