This paper aims to study the effects that asynchronous and synchronous instructional methods have on student perceptions and attitudes towards online education. We analyze both qualitative and quantitative survey responses from 496 students in three large (greater than 200 enrolled students) first-year calculus classes at the University of Guelph. The survey results show significant differences among the three online instructional formats in students' attitudes toward asking questions, the similarity of each instructional modality to face-to-face delivery, technology issues encountered, students' perceived ability to keep up with course content, how collaborative the course felt, and student preferences for mode of delivery. There were no significant differences reported in relation to time-management skills or communication with instructors. Qualitative analysis of student comments also revealed perceived strengths and weaknesses of each mode of instruction. The results are used to make suggestions for improving student experience in online, post-secondary mathematical teaching.