We report on an effort tomeasure the effect of replacing traditional lecture-based teachingin calculus with a flipped-classroom approach.We base the comparison between the twoteaching models on data fromthree sources: (a) a Calculus BaselineTest, designed specificallyfor this purpose and given as pre-test and post-test; (b) a survey measuring studentengagement; and (c) student achievement on the final exam. On the Calculus BaselineTest, we found that the normalized gain was 13% higher in the flipped-classroom group.Similarly, the flipped-classroom group scored significantly higher on the engagementsurvey. Also, the students of the flipped-classroom group performedmuch better than expectedon the final exam of the course, with a substantial decrease in failure rate.