The mastery of verb tenses and aspects is essential for criminology students, as precise grammar is crucial for professional communication in legal reports, case analyses, and investigative documentation. However, traditional grammar instruction often relies on rote memorization, which may not effectively support students in grasping complex grammatical rules. This study investigates the effectiveness of addition-based mathematical formulas as an instructional tool to enhance students' mastery of verb tenses and aspects. Grounded in Cognitive Load Theory (Sweller, 1994), Vygotsky’s Zone of Proximal Development (1978), and Piaget’s Cognitive Development Theory (1972), this research proposes that structured, rule-based learning can facilitate more effective grammar acquisition. A quasi-experimental research design was employed, involving 90 criminology students from a higher education institution in the Philippines. Participants were divided into an experimental group, which received instruction using addition-based mathematical formulas, and a control group, which was taught using traditional grammar instruction. Data collection involved pre-tests and post-tests to measure students' proficiency before and after the intervention. Statistical analysis using paired-sample t-tests and independent-sample t-tests was conducted to determine the significance of the results. Findings indicate that the experimental group (M = 38.045, SD = 7.427) significantly outperformed the control group (M = 29.974, SD = 8.054), with a t-value of 4.726 and a p-value of .000, indicating a statistically significant difference at p < 0.05. These results confirm that addition-based mathematical formulas effectively improve students' mastery of verb tenses and aspects by providing a structured, logical approach to grammar learning. The study highlights the pedagogical potential of interdisciplinary teaching strategies, particularly the integration of mathematical reasoning into language instruction. It recommends that higher education institutions incorporate mathematical structuring into grammar instruction, particularly for students in technical disciplines such as criminology. Additionally, further research should explore the long-term retention effects of this approach and its applicability in other linguistic domains, such as syntax and morphology.