Learning strategies are designed to support educational objectives, yet students' mathematical communication skills may remain limited when instructional approaches are insufficiently engaging. This study examined changes in the mathematical communication skills of second-grade students at MIS Al-Khairi Nagur Pane following the implementation of the Story Mapping strategy. A quantitative pre-experimental approach with a one-group pretest–posttest design was employed. All 17 second-grade students participated through saturated sampling. Data were collected using pretests and posttests and analyzed through instrument validity and reliability assessments, the Shapiro–Wilk normality test, and hypothesis testing. The mean score increased from 66.29 (SD = 7.12) on the pretest to 86.65 (SD = 5.21) on the posttest, representing an improvement of approximately 20.36 points. Normality testing yielded significance values of 0.983 for pretest scores and 0.588 for posttest scores, indicating no significant departure from normality. The hypothesis test revealed a statistically significant difference between scores (t = −23.508, df = 16, p < 0.001). These findings suggest that Story Mapping may be a useful strategy for supporting students' ability to express and communicate mathematical ideas. However, because the study involved a small sample, one group, and no control condition, the observed improvement cannot be attributed conclusively to the intervention alone. Further controlled studies with larger samples are recommended to assess its effectiveness across different primary school learning contexts. Such evidence could help teachers select appropriate activities for mathematics lessons.