Influence of English Language Proficiency on Subject Matter Comprehension and Academic Performance among Diploma Students in Tanzania. A Case of the Institute of Adult Education
Abstract
English language proficiency plays a critical role in facilitating learning in English-Medium Instruction (EMI) settings, yet many students in Tanzanian higher education institutions continue to experience challenges in comprehending academic content delivered through English. This study examined the relationship between English language proficiency, subject matter comprehension, and academic performance among diploma students at the Institute of Adult Education (IAE), Tanzania. Guided by the Sociocultural Theory and García's Translanguaging Theory, the study employed a convergent mixed-methods design involving 377 participants, comprising 334 diploma students, 32 lecturers, seven examination officers, and four quality assurance officers. Quantitative data were collected using questionnaires and an English Language Proficiency (ELP) test, while qualitative data were obtained through semi-structured interviews. Quantitative data were analysed using descriptive statistics, Pearson's correlation, and regression analysis, whereas qualitative data were analysed thematically. The findings revealed significant positive relationships between English language proficiency and subject matter comprehension (r = .641, p < .001) and academic performance (r = .513, p < .001). Qualitative findings further demonstrated that students with stronger English language skills understood lectures more effectively, participated more actively in classroom discussions, and performed better in academic assessments. The study concludes that English language proficiency is an important determinant of both subject matter comprehension and academic performance among diploma students. It recommends strengthening institutional English language support programmes, promoting learner-centred pedagogical approaches, and strategically integrating Kiswahili to enhance comprehension without undermining English language development