Learning from worked-out examples has been shown to be very effective in initial cognitive skill acquisition. In order to fully exploit the potential of example-based learning, teachers should, however, know how to effectively employ such examples in classroom instruction. Therefore, we have designed a computer-based learning environment in which mathematics and science teachers learn how to effectively employ worked-out examples. The learning environment was developed according to approved design criteria. The topics that are addressed in the learning environment were chosen in response to the results of a needs assessment that analysed schoolbooks and classroom videos, and took interviews with teachers into account. In experiments as well as in several teacher trainings on example-based learning, the computer-based learning environment was evaluated and improved accordingly. On a more general level, our research and development project showed that a computer-based learning programme could be a sensible tool that supports follow-up work in teacher training contexts.