In this study, a mobile device and online system, StudentPartner, is proposed to help students learn English on campus using multimedia and GPS support. Two activities, exploring the campus in English and English presentation, were designed to stimulate students' deep engagement and interaction with the system. Since students are very familiar with the campus as context, these activities elicit interest and playfulness. An experiment using the proposed system was conducted on the university campus for six months. The results show that positive perceptions of an activity, especially that of exploring the campus, significantly influenced users' intentions to utilize the proposed system. In addition, it was found that users' performance in the English presentation activity was significantly correlated with their achievement in learning. Thus, the proposed system, when combined with these two activities is an effective and enjoyable method of learning English that utilizes the concepts of contextual familiarity and the exchange of ideas through presentations. (Contains 12 tables and 12 figures.)