This module uses a well-developed Java tool created at the University of New South Wales and the University of Durham. The questions that were created around the Java tool have been reimplemented in the problem tree in order to provide additional framework for learning and feedback to the student. This module is an example of how additional web resources (Java, Flash, etc.) can be used in the problem tree environment. It is straightforward to embed any content in the learning environment, which reduces substantially the work involved in creating educational resources.