I heard recently from a feed about a great book called Fifty Dangerous Things (You Should Let Your Children Do).
With supervision, doing dangerous experiments teaches not only great science and allows for discovery. It also teaches judgment and safety skills. If no one teaches you how to be safe before you experiment with concrete and speed or a hairpin and electrical sockets, you're going to the ER. Safe experimentation is a really important life skill!
The key to it being really effective learning is the doing.
I'm huge on interactivity and constructivism. Some things, like learning to drive a forklift, are best learned with the real deal. However, other things... like software simulation for example... are easily replicated in the online environment. Drag and drop activities and picture hunts with roll over information hidden in them are two more examples of activity in an online, stand-alone training.
Here is a sample I did a couple months ago. (Click here to download.). Open this with any browser.
What's working? You see it; you do it. Seeing is better than telling, and doing is better than seeing. The repetition of seeing & doing defiantly helps for novice learners.