Students often complain about their perceived disconnect between the time and effort spent studying and their subsequent performance on exams. Robert Bjork's research asserts that retrieval of stored information acts as a memory modifier, and that using tests as learning events creates "desirable difficulties that enhance learning." To determine the effect of utilizing testing as a learning event in the introductory (majors) biology classroom, we used an online homework platform to give required quizzes throughout the course. Analysis of exam grades earned by those taking 100% of pre-exam quizzes indicates that not only does this group have a significantly higher exam average than the group of students who took 0% of the pre-exam quizzes, but they also have a significantly higher exam average than the class average. Through detailed, statistical analysis, the benefit of quizzing is demonstrated to be significant for students of diverse academic abilities. Pre-exam quizzing using an online homework platform is an effective way to increase student performance on exams and allows class time to be utilized for teaching activities.