(Creative Commons image: Jesper Hauge)Science (on sale!) without the mess.
Title: Piiig Labs
Pricing: Paid (but currently on sale!)
Platform: iOS (Apple)
Summary: All the classic science fair experiments (baking soda/vinegar volcanos, simple circuitry, etc.) plus a few extra oddball types (theremin, anyone?) presented in a virtual setting with no mess and no danger. Granted, the fun part of most of these experiments IS the mess and the danger, but this is a great way to introduce the concepts, let kids practice setting them up a few times before considering letting them loose on the real thing. Plus, Venus flytraps in real life sort of give me the creeps.
If you like this, try: doing some of the science experiments in real life! The volcano one is pretty simple (especially if you're not picky about your volcano looking exactly like a coffee mug) and the circuitry one could easily translate into the squishy circuits project. For that last one, you'll likely need to buy a few inexpensive electrical components, but they're reusable and this project is so fascinating and fun for kids that you'll want to be able to do it over and over again anyway.