The purpose of this study was to investigate the effect of explanation assisted REACT strategy which was based on context-based learning approach on prospective science teachers' (PSTs) learning in impulse, momentum and collisions topics. The sequential explanatory strategy within mixed methods design was employed in this study. The first phase of the study in which quantitative data were collected represents the experimental aspect of the study, the second phase of the study in which qualitative data were gathered to support quantitative data represents the descriptive dimension. The study was carried out with 25 PSTs in the experimental and 25 in the control group. In this study, two-tier Impulse, Momentum and Collisions Concept Test (IMCCT) were used as a data collection tool. IMCCT which was consisted of 34 questions was administered as pretest before the intervention, posttest after the intervention and delayed test 9 weeks after the intervention. This study revealed that explanation assisted REACT strategy which was based on context-based learning approach was found more effective than the traditional teaching approach on impulse, momentum and collisions topic. Findings also showed that some of the alternative conceptions were significantly eliminated in the experimental group.