Students' performance in introductory physics at a university in Ghana was assessed over three academic years. The study covered two physics courses delivered to first-year students at the university. Two factors--access to tutorial sessions delivered outside of lecture times by teaching assistants and access to a formula sheet during the exams--were studied. The impact of the factors on students' performance was studied by comparing student scores, item difficulty levels, point biserial correlation coefficients, and internal discrimination index for a set of questions that were common to all the exams. The effect of both factors was an increase in the item difficulty from 0.60 ± 0.09 for the control group to 0.63 ± 0.19 for the treatment group, while the effect of the formula sheet increased from 0.60 ± 0.16 to 0.64 ± 0.20. The point biserial correlation coefficient did not change for the study on the effect of the provision of formula sheets in examinations, but it was statistically significant for the group that had separate tutorial sessions. The findings suggest that more learning outcomes can be achieved using interactive teaching approaches and favouring the least amount of rote learning of physical formulae.