This study was a classroom-based action research. In this study, constructive teaching and learning activities were used to help learners improve on their grammar and usage with a focus on how to help them internalize subject verb agreement rules. The purpose of the research was to assist learners to improve upon their performance in grammar and usage. This action research aims to explore how constructive teaching and learning activities which are learner-centered activities can help learners to overcome their subject verb agreement errors and to improve on their English grammar and usage. Seventy eight (78) Level 100 (first year) students from the Faculty of Science, University of Education, Winneba took part in the study The study started with a pre-test in grammar and usage. This was followed by two focus group discussions. The students were then taken through the intervention designed by the instructor. Constructivists' activities were used to guide the students to correct errors in their sentences. After the intervention, the students were interviewed about their impressions. There was a post-test at the end of the intervention. The outcome of the study showed an improvement in students' performance in grammar and usage.