Here is the 'Simple Machines' app I have been working on with Tinybop - out now in the app store.
http://tinybop.com/apps/simple-machines
https://itunes.apple.com/app/apple-store/id936966570?mt=8
DISCOVER HOW SIMPLE MACHINES WORK
Use a lever, screws, wheels and axles, inclined planes, wedges, and pulleys to send satellites into orbit, split an iceberg, make music, and more!
CONDUCT YOUR OWN EXPERIMENTS
Change each machine and see what happens: can a scooter travel as fast and far as a bike? How many pulleys do you need to lift a spaceship?
INVESTIGATE INVISIBLE FORCES
See how each machine changes the direction, distance, or strength of your force. How do they make it easier to destroy the castle or lift a fish tank?
KEEP LEARNING
A free companion to the app, the Simple Machines Handbook, supports STEM education and highlights activities for transferring in-app lessons to the real world.
LEARN IN 40+ LANGUAGES
Interactive labels in 40+ languages, including Chinese, Russian, German, French, Spanish, Japanese — and more!