The Effect of Mother Tongue Instruction on Adult Literacy Acquisition in Multilingual Communities in Nigeria

This study examines the effect of mother tongue instruction on adult literacy acquisition outcomes in multilingual Nigerian communities, providing empirical evidence on the language-of-instruction debate in Nigeria's adult education system. National adult education programmes predominantly use English or Hausa as instructional media, despite Nigeria's estimated 500 languages and strong evidence from children's education research that mother tongue instruction improves early literacy outcomes. Whether similar effects hold for adult learners in multilingual Nigerian communities has not been rigorously tested. This study uses a randomised controlled trial design, randomly assigning 300 adult learners in multilingual communities in Cross River, Kogi, and Plateau States to either mother tongue-medium or English-medium literacy classes over six months. Literacy acquisition is measured at baseline, midpoint, and endline using validated Yoruba, Igala, and Tiv language assessment tools alongside English reading assessments. Regression analysis with randomisation balance checks is applied. Findings reveal that mother tongue instruction produces significantly higher literacy acquisition rates at six months compared to English-medium instruction, with effect sizes of approximately 0.4 standard deviations. Transfer to English literacy is evident in mother tongue groups after six months, suggesting effective bridging. Older learners show stronger relative benefits of mother tongue instruction. The study concludes that mother tongue instruction is superior to English-medium instruction for initial adult literacy acquisition in multilingual Nigerian communities. It recommends a mother tongue-first language policy for the first six months of all adult literacy programmes in non-English mother tongue communities.

Keywords: mother tongue instruction, adult literacy, multilingual communities, language policy, Nigeria.