This study investigated the difficulties in the transition period in Mathematics from Mother Tongue to the English language of the grade 4 pupils in the North Sector of Magalang in the Division of Pampanga. The study used a validated researcher-made instrument to identify the least learned topics as well as what category the lessons belong based on the curriculum guide. Based on the results of the questionnaire, the least learned item was multiplication in an appropriate worded problem, and most of the difficult items fell under the category of comprehension where students find difficulty in analyzing test questions. It revealed that students have difficulty in identifing terms, understanding sentence and grasping the language used in mathematical sentences. The teacher-informants suggested providing real-life examples, creating more activities and exercises, giving motivating time-lapsed activities, providing remedial lessons, making the language use easy, making local and contextual lessons, giving constant practice as the possible solutions in improving the pupils' performance in Mathematics. The study used statistical tools, such as frequency, mean, and dtandard deviation to interpret the data needed. With the results of the study, the researcher designed and created a transition plan based on the difficulties of the informants in Mathematics in connection with word recognition, comprehension and language use. May the transition plan in Mathematics serve as supplementary material for the teacher-informants who are having difficulty in teaching the grade four pupils from the Mother Tongue shifting th English language use.