Flipped learning is a well-recognized learning mode that reverses the traditional in-class instruction arrangement by delivering learning content outside of the classroom and engaging students in more activities in class. However, it remains a challenge for students to comprehend the learning material by themselves, particularly when learning abstract concepts such as in mathematics. In this study, an interactive e-book approach is proposed to support flipped learning. It facilitates and bridges out-of-class and in-class learning by providing support for interactive learning contents presented on mobile devices. To evaluate the effectiveness of the proposed approach, a quasi-experiment was conducted in an elementary school math course. The experimental group students learned with the interactive e-book approach in the flipped learning activity, while the control group students learned with the conventional video-based flipped learning approach. The experimental results indicated that the proposed approach not only promoted the students' self-efficacy for learning mathematics, but also improved their learning achievement; moreover, it was found that the approach benefited the lower self-efficacy more than the higher self-efficacy students. The learning record analysis further confirmed that the lower self-efficacy students spent more time reading the e-books before and in class than the higher self-efficacy students did.