Soup Toys is a free download game. You play it straight on to your desktop. It allows you to set up different sequences and contraptions using different items. You can keep your desktop as the background or choose a blue background.
It is a great tool for problem solving, predicting results, physics and decision making. You can also record each sequence and save them.
A great activity would be to set a few limits for students and see the different results they create.
Eg. You can only use three levers and five balls or build a castle to house four dolls.
It is also a lot of fun just to play with.