In this paper, we present new technologies that can be used in lectures to increase the activity and motivation of students. The poor communication between students and teacher is one of the major problems in mass lectures. However, mobile devices can reduce this problem and by improving the interactive communication help to increase the motivation of the students. We have implemented a set of interactive services, which have been tested and evaluated in several lectures and courses of our computer science and psychology department. In particular, we present a participatory simulation in form of a stock exchange. Users taking part in the computer-based simulation become private investors who are able to buy and sell securities. Participating in the simulation facilitates the understanding of the complex system of a market and increases the activities of the students.