Decoding Mathematics: Pupils' Performance and Teachers' Pedagogical Challenges in L1 and L2 Word Problem Integration in Tumauini South District, Isabela for the School Year 2025–2026

Language is important when learning mathematics, especially with word problems. Understanding the language used in these problems is key to solving them correctly. This study examined how well Grade 3 students solved math word problems in their first language (L1) and second language (L2) and explored the challenges teachers face when using both languages in their teaching. The research involved 60 students and four teachers from Lapogan Elementary School in Tumauini South District, Isabela, but only 55 student responses were analyzed because some data were incomplete. A 15-item test created by the researchers was administered in both L1 (Ilocano) and L2 (English), along with interviews and analysis of students' academic performance. The data were analyzed using the mean, standard deviation, Z-test, and F-test. The results showed that students did better in L1 (M = 11.16, SD = 2.51) than in L2 (M = 9.85, SD = 2.61), with a significant difference (p < 0.05). Similarly, their academic performance in the second grading period (L1) was slightly higher (M = 82.67, SD = 6.08) than in the third grading period (L2) (M = 81.93, SD = 6.60), with significant differences noted. These findings suggest that the language used in teaching greatly affects students' understanding and problem-solving skills. Teachers also mentioned challenges such as limited teaching materials, vocabulary issues, and insufficient training in multilingual teaching methods. The study concludes that using L1 helps improve mathematical understanding and leads to better learning outcomes, while moving to L2 requires structured teaching support.