The effect of two instructional variables, manipulation of objects and guidance, in learning to use the logical connective, conditional, was investigated. Instructions for 72 first- and second year social science students were varied in the computer-based learning environment Tarski’s World, designed for teaching first-order logic (Barwise & Etchemendy, 1992). Guidance, which was operationalised by giving the learners problems that guided them to all different types of basic problem situations that could be derived from the conditional by stimulating them to manipulate or to imagine to manipulate the geometrical objects, significantly influenced the scores from pre- to post test. Manipulation, which was operationalised by giving the learners a visual representation in which (concrete) geometrical objects could be manipulated, yielded significant results from post- to retention test. The results support the authors’ view that guidance in combination with the possibility to manipulate objects in a domain, support the acquisition of knowledge and skills in that domain. Guidance leads to the students seeing all situations that are relevant for the development of new knowledge, which has a positive effect directly after instruction. The possibility to manipulate leads to the students playing around in such a way that they (systematically) experience the results of their actions by the feedback given, having an effect after two weeks of non-instruction.
- Logical reasoning - logic teaching - problem solving - computer-based instruction - guidance - manipulation