Abstract
Challenges hindered mathematics performance among upper-primary Thai students in reasoning and problem-solving within bilingual education. This descriptive-correlational study examined the influence of student engagement and English proficiency on mathematics performance and identified key predictors of success. Data were collected through standardized English and mathematics tests and a student engagement survey and analyzed using descriptive statistics, correlation, and regression. Findings revealed that students exhibited high behavioral engagement (M = 4.72, SD = 1.08) but lower affective (M = 3.67, SD = 1.03) and cognitive engagement (M = 3.62, SD = 1.04), indicating active participation but limited deeper conceptual involvement. Most students had intermediate English proficiency (M = 45.45, SD = 27.63), with 35.2% at B2 and 21.76% at B1. Mathematics performance was highest in computation (M = 4.28), followed by reasoning (M = 3.97) and problem-solving (M = 3.78). While student engagement did not significantly influence mathematics performance (p > .05), English proficiency showed a moderate positive correlation (r = .348, p < .05). English proficiency was the strongest predictor (β = .356, p < .05), with student engagement contributing to a lesser extent (β = .171, p < .05). The overall model was significant (R = .387, R² = .150, F = 1.68, p = .000). These findings underscored the need for bilingual instructional support, language scaffolding, and strategies to foster deeper cognitive engagement. The study recommended strengthening English proficiency, integrating student-centered learning, and creating a supportive classroom environment to enhance Mathematics learning outcomes.
