In very large lecture classes, student engagement is always a challenge, and many instructors use electronic student response systems (SRS) to promote student engagement and active learning. The conventional wisdom in using student response systems is that the technology matters less than the pedagogy; it is the added value of the instructor that makes the technology successful. We explore the impact of different student response systems in successive years in a general education human biology course, BIOSCI 201, Human Form and Function. Taught by the same instructor using the same textbook, the course used different SRS in three successive spring semesters. Analysis of student assessment data in the lecture portion of the course indicates a statistically significant impact of the use of SRS by students on their grades and a statistically significant difference in the magnitude of that impact when using different SRS.