Recycle that water bottle, and make a cool sand art pendulum.
This is a nice project for the kids on a day when you can't go out and play. This entertained them for hours. But when you're all done, you WILL need to vacuum, and they WILL need to take a bath.
You will need:
a water bottle
a big piece of cardboard
salt or sugar (or sand)
a needle, or drill bit, or awl. (something to poke some holes.)
Step 1: Build Your Pendulum
Take an empty water bottle, and cut off the bottom. Poke three hole equally spaced about 1/4" from where you cut. Tie a sting to each hole. Tie strings together at the other end. All 3 strings should be the same length.
Now take the cap, and drill a hole through the top. (about 1/4" diameter)
Step 2: Hang It Up
Now hang your pendulum from something. We hung ours from our light fixture, but you can hang it from the ceiling, a door frame, or just hold it.
You can tie a string to the end of your 3 stings, to make it long enough. You'll want it about a foot or less above the table top. (or floor)
Step 3: Fill 'er Up
Now it's time to fill up the bottle. I used Salt. You can use sugar, but your little ones might spend more time eating it than playing. You could use sand if you had some.
Fill the bottle while holding your finger over the hole in the cap. Get ready to remove you finger and give it a good swing. (Not too hard, or you'll shoot salt across the room.)
Make sure the bottle is DRY. If there is any water in there, the salt with clump, and it will not flow out.
Step 4: Let It Swing.
Let is swing around. Give it a twist to make some interesting patterns. Let the little ones try to catch it, and send it off. If your little ones are bigger, go ahead and share all your knowlegde of pedulums, and Foucault pendulums.
Step 5: Do It Again.
Since you made your salt art on your handy cardboard, you can fold it, and pour the salt back into a cup. Then pour that salt back into the bottle and do it all over again. See how many different patterns you can get. Find out what happens when you swing hard, slow, with a twist, etc.
Step 6: Freestyler
Once you get sick of the pendulum, you can draw freestyle with the bottle. The kids have fun drawing in the salt with their hands. Combs make fun patterns too.
Hope you have lots of fun with this. Don't mind the mess, it's easy to clean. Now throw them in the bath, and wash off all that salt.