Assessing the efficacy of the concrete-representational-abstract instructionalsequence in teaching basic addition facts to students with mild intellectualdisability

Objectives: To assess the efficacy, maintenance, and applicability of the concrete-representa-tional-abstract (CRA) instructional sequence in teaching basic addition facts to students withmild intellectual disabilities, focusing on the evolving nature of commutative properties.Methods: Three students with mild intellectual disabilities, aged between 8 and 11 wererecruited for participation in the research. A multiple-probe design with probe trials across par-ticipants was conducted.Results: The results show a functional relation between the CRA instructional sequence and theacquisition of basic addition by students with mild intellectual disabilities. Furthermore, the stu-dents demonstrated the ability to sustain this skill one to two weeks later and to generalise itto scenarios reflecting commutative properties (3 þ 2 ¼ ? instead of 2 þ 3 ¼ ?). Conclusions: The implications for both practical application and further research pertaining tothe CRA instructional sequence were deliberated upon in this study.