The English language serves as the primary medium for technology, commerce, and various other fields, which draws people from across the globe to learn English as a second or foreign language. English serves as the primary medium of instruction in Ugandan schools, yet a significant portion of students in rural areas struggle with grammar, hindering their ability to participate effectively in classroom discussions, oral examinations and daily communication. It is against this background that the study assessed the effect of grammar on English language proficiency among secondary school students in Mukono district, Uganda. Skinner’s (Verbal behavior, Copley Publishing Group, Acton, 1957) Behavioral Theory of Language Learning underpinned the study as it posits that behavior, including language learning, is shaped by environmental stimuli and responses, with reinforcement playing a critical role in strengthening desired behaviors. The study employed a cross-sectional research design using a mixed-methods approach, integrating both quantitative and qualitative methodologies. Quantitative data were collected from 176 Senior Three students using questionnaires, whereas qualitative data were gathered through interviews from 12 English language teachers. Quantitative data were analyzed using SPSS while Qualitative data obtained from the interviews were analyzed using thematic analysis. The results indicated that students who were able to apply correct grammatical structures performed better in writing and speaking assessments. The study concluded that mastery of grammatical structures such as tense usage, sentence construction, and punctuation was found to directly influence students’ performance in both written and verbal communication. The study recommended that teachers should integrate grammar teaching into speaking, writing, and reading activities, focusing on real-world applications.
Kibbumba et al. (Wed,) studied this question.