Click it. I have a real one, at home.
This works the same way, but doesn't need to be dusted off.
Oh. I'm in New Mexico. Some people live without so much dust.
If that's not working on your computer, click here for another. It's Less elegant, but change the number up top left, and click "play." You can mess with the balls as they're moving.
And another cool pendulum thing, kind of a cross between the physics of music, and the art made by wrapping stringing across a pattern of nails on a board. Trippy hippy stuff. (And physics pattern stuff.)
There are homeschool science fairs. Anyone who doesn't know that probably should know. There are school-at-home families who make their kids do a science fair project. Unschoolers don't do that (though it's possible that there have been unschooled kids who have found out about those fairs and asked their parents please PLEASE to help them with a project and to buy them one of those folding display boards! Maybe. )
Susan Messina, photo and art (found on George Takei on facebook)
When I put that image and some questions about what parents thought about science, and whether such display boards and science fairs existec outside the U.S., there were lots of friendly, sensible answers, and one that led to some problems. I've preserved it without the name of the commenter.
Scientific method is touched on, and some other logic issues.