Some days it's hard to get the kids to go outside. Today I found something that they were all (eventually) interested in trying, and they learned a little bit too!
I remember doing wood engraving with a magnifying glass when I was a kid. It took a little longer to do here than I remember, but then we are 6,683 feet further away from the sun.
All you need to engrave wood with a magnifying glass is a sunny day, a piece of wood, and, well, a magnifying glass. A steady hand is a plus, too. Just focus the light "just so" and hold it until you see the thin trail of smoke. Then, slowly burn your design onto the wood. It's a little light-intense, so take little breaks to rest your eyes. Sunglasses might be a good idea.
We discussed a little bit about if you were stuck in the wilderness (or otherwise needed a fire and didn't have a lighter or matches), you could use a magnifying glass....or your glasses (though we didn't test that one out) to get a fire started.
This should be a supervised project with young kids - keep safe out there! And of course stress the importance of being careful and responsible with fire.
It works to light smoke bombs, too. :)