Objective: This study aims to determine the effectiveness of the concrete-representational-abstract (CRA) sequence presented by the explicit instruction in teaching the skills of basic addition and subtraction, building tens-and-ones to a student with special needs in a general education classroom. Method: A multiple probe across skills single case research design was used to evaluate the CRA sequence. The research was carried out with a seven-year-old female student diagnosed with autism spectrum disorder (ASD). Results: It was determined that the participant gained the math skills taught with the CRA sequence, and these skills were displayed two, three, and four weeks after the intervention ended. In addition, it was observed that the student was able to generalize these skills to another environment and person. Social validity findings show that the mother has positive opinions about teaching math skills with CRA sequence. Conclusion: In this study, it was determined that the CRA sequence could be used effectively in teaching math skills to a student with ASD studying in a general education classroom.