<p>Brief pre-class physical exercise may enhance executive function (EF) processes proximal to mathematics learning. However, the effect is likely dependent on the alignment between the physical exercise and subsequent instructional demands. We tested a dual-process framework in authentic classrooms, predicting selective gains in mathematics-specific inhibitory control rather than broad executive function. Using a cluster-randomized trial, four Grade-5 classes (<i>N</i> = 182 students) were assigned to mentally passive sedentary behavior (e.g., video watching), mentally active sedentary behavior (e.g., numeracy practice), 5-minute physical exercise, or 10-minute physical exercise. EF outcomes were assessed at baseline, immediately post-intervention, and after the mathematics instruction using a domain-general flanker task and a mathematics-specific negative priming task. Both physical exercise groups outperformed mentally passive sedentary behavior on the inverse efficiency score of the negative priming task at post-instruction, with no differences between 5- and 10-minute physical exercise, and no consistent advantages on the flanker interference performance. These results support a task–context alignment mechanism in which brief physical exercise may prime motivational/alerting states that translate into improved inhibition when followed by domain-relevant instruction. Short, pre-class physical exercise routines can be integrated without displacing teaching time and may enhance readiness for mathematics learning by selectively improving mathematics-specific inhibitory control. We discuss implementation parameters for classroom use and implications for theory on how physical exercise influences psychological processes central to learning.</p>