This study aimed to examine whether withholding answers coupled with physical manipulation of material strengthened by the self-explanation effect (SEE) contribute to the development of a deeper conceptual understanding and retention of learning about motion content in a hands-on (HO) learning environment. The correlation between students' self-explanations and their results on both the post-test and re-test was analyzed. N = 100 third-graders (9--10 years) were divided into the following groups: IIHO (indirect instruction + independent performance of HO -- withholding answers + physical manipulation), DIHO (direct instruction + observation of HO performance -- no withholding answers + no physical manipulation), IIHO + SEE and DIHO + SEE. The ANCOVA analysis shows that the students in the IIHO + SEE and DIHO + SEE groups showed significantly higher achievements within the examined variables over the IIHO and DIHO groups. A strong positive correlation was observed between student self-explanations and the results of both tests.