This study established the effects of a researcher-developed curriculum-based intervention programme. The intervention was grounded on principles of Feuerstein's ideas about 'mediated learning'. The aim of the intervention was specifically to address children's executive functions, which are generally regarded as prerequisites for cognitive development. We studied a selected group of South African grade R learners (n = 20). A quasi-experimental design was employed to collect quantitative data on rotational basis from experimental groups A and B, by means of dynamic assessment with the Children's Inferential Thinking Modifiability (CITM) test during pretest, post-test and delayed post-test occasions. The test data was intended to elicit the extent to which the intervention that had focused on enhancing executive functions had contributed to the participants' application of cognitive and metacognitive skills and strategies. Qualitative data captured participants' application of cognitive processes in the input, elaboration, and output phases of the designed learning process, as well as the characteristics of their inhibitory control functions. A striking finding was the improvement noted in the children's application of the following executive functions, namely working memory, cognitive flexibility and inhibitory control.