Flipped classroom is an instructional model in which basic subject matter knowledge is learned prior to in-class sessions, and active learning experiences happen in class. To address a gap in recent research regarding students' pre-class learning design and its effect in flipped classrooms, an experimental study was conducted to investigate pre-service teachers' pre-class learning effects in a flipped classroom course. The control group completed their pre-class learning by viewing ordinary videos. Treatment group I completed their pre-class learning by viewing interactive videos with pop-up questions based upon the Knowledge Integration theory. Treatment group II completed questions which were based upon the Knowledge Integration theory on discussion boards before and after viewing the videos. All three groups had the same instructor, classroom learning activities, and learning evaluation approaches. This study found that the learning achievement and self-efficacy of the learners in the two treatment groups were significantly higher than those in the control group. In addition, the pre-class learning experience designed by the Knowledge Integration theory was well received by the learners in the flipped classroom. The pre-service teachers in the two treatment groups also indicated that these pre-class learning experiences could better promote the relationship between their learning and their subject teaching work in the future.