Physics Class recently completed the mechanical energy section of Physics. To conclude this section each class was contracted to build a Rube Goldberg machine. A Rube Goldberg machine is an overly engineered machine that is constructed to perform a simple task.
Each class had to choose two leaders to be in charge of the class. The class was then "contracted" to plan, build, film, and clean up the machines in a two week period. Just like in a real world contract, the students were responsible for all aspects of the project with no outside supervision. Discipline, planing, and testing were handled completely by the class and the leaders themselves.
After days of testing and literally hundreds of tries I think you will be pleased with the results.