Controlling Variables: testing a programme for teaching a general solution strategy

Abstract
Detail is provided of a theoretically based teaching programme designed to induce students to construct a mental scheme in which experimental design and natural experiments (Kuhn & Brannock, 1977) are understood as facets of the same problem, and which incorporates a general solution procedure applicable to both. A pre‐test‐post‐test‐delayed post‐test controlled examination of the efficacy of the programme is described using grade 8 students as subjects. The results show a highly significant post‐test achievement increase by the experimental group over the control, which is retained in the delayed post‐test. Evidence is also presented indicating a probable decrease in performance decalage between planned and natural experiments by the experimental grade 8 group.