Various methods have been proposed in the past to improve student learning by introducing new styles of working with assignments. These include problem-based learning, use of case studies and apprenticeship. In most courses, however, these proposals have not resulted in a widespread significant change of teaching methods. Most institutions still use a traditional lecture/lab class approach with a strong separation of tasks between them. In part, this lack of change is a consequence of the lack of easily available and appropriate tools to support the introduction of new approaches into mainstream courses.In this paper, we consider and extend these ideas and propose an approach to teaching introductory programming in Java that integrates assignments and lectures, using elements of all three approaches mentioned above. In addition, we show how the BlueJ interactive programming environment [7] (a Java development environment aimed at education) can be used to provide the type of support that has hitherto hindered the widespread take-up of these approaches. We arrive at a teaching method that is motivating, effective and relatively easy to put into practice. Our discussion includes a concrete example of such an assignment, followed by a description of guidelines for the design of this style of teaching unit.