Pre-class learning plays a crucial role in the teaching and learning of the flipped classroom. While it is a challenging task to stimulate students to engage in pre-class autonomous learning, especially for the learning of a foreign language that requires a long-term commitment. In this study, we dealt with the problem of how to improve and maintain students' motivation in pre-class learning of a foreign language. First, we devised a motivational model with factors that encourage student engagement. Then, we developed motivational strategies based on the model to motivate students to be highly engaged before class in this pilot study for a Chinese course for beginners at Tokyo University of Technology. Using a Moodle learning management system, we established a framework for pre-class learning materials and collected data by keeping track of pre-class learning activities and extracting student perceptions and evaluations of their pre-class learning experience. Statistical analysis of the data for three academic years shows that the motivational design used for the flipped classroom effectively enhanced students' behavioral engagement and accordingly increased academic outcomes. The practice of the flipped classroom with motivational design is of particular significance for foreign language teaching and learning. The motivational model and the instructional design for pre-class learning have the potential to be used for other foreign language courses.