Language of Instruction and Learning Outcomes: Examining the Use of Kiswahili in English Language-facilitated Courses at Tanzania Public Service College

Abstract

This study examines the complex relationship between the language of instruction and learning outcomes in English language-taught courses offered by public service institutions in Tanzania, with a specific focus on the strategic use of Kiswahili. Guided by Translanguaging theory, the study adopted a qualitative research approach and selected Tanzania Public Service College (TPSC) - Mtwara Campus as its case study. Data were precisely gathered through in-depth interviews with students and instructors, systematic classroom observations, and comprehensive documentary analysis. Findings reveal that despite official English-only policies, translanguaging practices, particularly the use of Kiswahili, are prevalent and deliberately employed by both instructors and students. Participants reported that Kiswahili facilitated comprehension of complex concepts, reduced anxiety, and enhanced students’ participation, acting as a crucial scaffolding mechanism. However, some concerns were raised about potential over-reliance, which could hinder the development of advanced English proficiency. The study concludes that careful and principled translanguaging serves as a pedagogical tool, optimising English language acquisition by leveraging students’ full linguistic repertoires. These insights carry significant implications for reevaluating language education policies, informing teacher training programmes, and designing curricula that better embrace multilingual realities in Tanzanian colleges.