LANGUAGE AS A GATEKEEPER: THE SOCIO-CULTURAL IMPLICATIONS OF MEDIUM OF INSTRUCTION FOR MARGINALIZED LEARNERS IN NIGERIA
Language plays a pivotal role in shaping educational access, participation, and success, particularly in multilingual societies where the language of instruction often determines learners' opportunities for academic achievement and social mobility. In Nigeria, the National Policy on Education advocates the use of the mother tongue or the language of the immediate environment during the early years of basic education, followed by a gradual transition to English. However, widespread reliance on English as the dominant medium of instruction has created significant barriers for learners from marginalized linguistic, cultural, and socio-economic backgrounds. This paper critically examines how the medium of instruction functions as a gatekeeper that either facilitates or restricts educational opportunities for marginalized learners in Nigeria. Adopting a systematic literature review methodology, the study synthesizes evidence from peer-reviewed journal articles, government policy documents, UNESCO reports, and empirical studies on language-in-education policies. The review reveals that the dominance of English in classroom instruction often disadvantages children from rural communities, minority language groups, nomadic populations, internally displaced communities, and economically disadvantaged households by limiting classroom participation, literacy development, academic achievement, and cultural affirmation. The paper further argues that language is not merely a medium of communication but also a mechanism through which social power, identity, and educational inequality are reproduced. Effective implementation of multilingual and mother tongue-based education is identified as a critical strategy for promoting inclusive, equitable, and sustainable education in line with Sustainable Development Goal 4. The study concludes that achieving educational justice in Nigeria requires stronger implementation of language policy, investment in indigenous language development, enhanced teacher preparation, and sustained stakeholder engagement. These measures will help transform language from a gatekeeping mechanism into an instrument of inclusion, empowerment, and national development.