The shifting of language as a medium of instruction in Philippine schools has significant effects on the learning performance of the students. Grade 1 to 3 used Mother as their medium of instruction by the time they reach grade 4, the language of instruction will shift to English. This paper aims to further analyze if shifting is something to consider as positive. Mixed-method design specifically explanatory sequential design was used to collect and analyze quantitative data through an

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... on and then obtained qualitative data through interviews. A Likert scale was used to reveal that there is no significant difference in the performance of the pupils who used Pangasinense and English as a medium of Instruction. Since most of the results were interpreted as a beginning, it evidently shows that the pupils at this level struggle with their competency; prerequisite and fundamental knowledge and skills have not been acquired or developed adequately. Therefore, the shifting then of the language can affect the learning ability of the student but not the language itself.