We took our Webelos to OMSI (the Oregon Museum of Science and Industry) a few weeks ago. There was some cool things in the Physics lab.
This is a sample of Aerogel – the least dense solid known to man. They call it “frozen smoke”. It’s 99% air, but very strong, and makes a great insulator. It’s used in a lot of space projects. You can actually buy a small chunk of Aerogel from United Nuclear, though it’s pretty expensive.