This study used a posttestonly non equivalent groups design involving undergraduate students in three sections of a General Chemistry course at an R-1 institution in the Midwest. Students in the control group (spring 2012) attended class 3 times a week (150 min per week) in a theater-style classroom with 350 students (Fig. 2). They listened to lectures, watched demonstrations, and responded to the instructor's questions and prompts. During the following semester (fall 2012) the experimental group was split into three sub-groups; each sub-group attended class just once a week (50 min per week) in an ALC with capacity for 117 students. They had access to optional online lectures, solved problems in small groups during class, worked with computer simulations, played a chemistry version of the game Jeopardy, and answered clicker questions. A second experimental section of the class, also in blended/flipped format, was held in spring 2013 as a replication.