The current study demonstrates how conceptual and procedural knowledge can be used as a heuristic to better understand student math difficulties in order to develop interventions and lay the groundwork for future research. Math interventions were implemented with two elementary students using a nonexperimental single-case design. One student demonstrated acceptable conceptual understanding but low procedural knowledge, and the other student demonstrated low conceptual understanding in addition to difficulties with procedural knowledge. The mismatched intervention (e.g., procedural for a student who needs a conceptual intervention) was implemented first for both students, followed by the appropriate intervention. The intervention that was identified as the most appropriate was more effective than the mismatched intervention for both students.The mean percentage of nonoverlapping data was 100% for the matched intervention and 16.5% for the mismatched intervention. Suggestions for future research are included.