This document is a research proposal that aims to study the effectiveness of using code-switching in classroom discussions for Grade 12 students at Agusan del Sur National High School in the Philippines. It discusses code-switching as a phenomenon used in bilingual societies and classrooms. The literature review covers grammatical theories of code-switching and the use of mother tongue-based multilingual education. The research questions examine students' English proficiency with and without the use of code-switching, as well as any differences between pre-tests and post-tests both with and without code-switching. The null hypotheses state there will be no significant differences found.