In this paper we present a new teaching paradigm based on ubiquitous computing, which we call the Interactive Lecture. It specifically supports situations where the interactivity between students and lecturer is usually limited, such as lectures with a large number of students, or teleteaching scenarios. In an Interactive Lecture each student is equipped with a handheld computer. These computers connect to the computer of the lecturer via wireless communication. Interactivity between students and lecturer is then increased by a number of services. Examples for these services are: online-feedback which enables students to give immediate feedback about the lecture (e.g., about its speed and difficulty), or online-quizzes were all students participate in solving problems described by the lecturer. We have developed a first prototype of the software and performed a thorough evaluation during a graduate course. The results of this evaluation indicate that interactivity was increased significantly and that the students were very enthusiastic about participating in Interactive Lectures in the future