I’ve been roped into being a “mad scientist” for a 7-year old’s birthday party. Anyone have recommendations for fun science experiments that will entertain a dozen kids on a sugar high? Some of the things already on my list:
[ul]
[li]Making slime (PVA and borax)[/li][li]Diet coke and mentos[/li][li]“Elephant toothpaste” (hydroden peroxide and KI or yeast)[/li][li]Air pressure experiments - dry ice in a bottle with a balloon over it; heat a can with a little water, then seal it and cool[/li][/ul]
Liquid Nitrogen Ice Cream
Shrinking marshmallows with liquid nitrogen
Putting a full place setting (including glass of water) on a smooth tablecloth & removing said tablecloth without disturbing the place setting (this requires an unhemmed piece of cloth made from very smooth, shiny material)
If you have a good vacuum pump and a clear evacuable chamber, you can put marshmallows in the chamber, suck the air out, and the marshmallows get bigger.
Pour a bunch of nails in a bucket and swing the bucket in a swift vertical circle–the nails won’t fall out. Then do it with water. (Water won’t fall out either.)
Quicksand in a bucket.
Take a bucket full of sand. Buy a bag or two of sand from the local hardware store for a few bucks. Put a water hose so that it feeds into the bottom. Put a brick on top of the sand. SLOWLY increase the water flow, starting from zero. When you get the flow rate up JUST enough, that brick will drop like…well…a brick in quicksand.
Starch and water. Mix the two until its a thick paste/liquid. You can pour it from container to container. It will run through your fingers. Quickly make a ball of it and throw it at something like the driveway. It will SHATTER, then the scattered shards will melt back into a liquid.
Take your starch and water paste - cover a speaker in plastic wrap (REALLY REALLY WELL) and put the mixture on top. Play music. Works best with deeper tones.
Baking soda and vinegar rockets.
A friend of mine does a participatory kid’s science show. His big finish is to demonstrate Bernoulli’s principle. He has a leaf blower with a paint roller frame taped to the nozzle. He puts a roll of toilet paper on the paint roller frame and uses the blower to propel endless streamers of toilet paper all over the audience.
That reminds me of something similiar.
Take a leaf blower, hair dryer, or shop vac set to blow, maybe even a big box fan.
You just need a strong stream of air. Put in that stream something like a ping pong ball or small inflatable beach ball.
Obviously, if the stream is straight up, the ball levitates quite high. The more interesting thing is the ball will stay in it rather than fall out of it. The even more interesting thing is you can direct the stream significantly from vertical and the ball will STILL stay in the stream and you’ll have it levitating off to the side. The bigger the stream and the smaller the ball the better it works.
There’s always the disappearing liquid trick – pour one cup of alcohol into two cups of water. You end up with only two and a half cups of liquid.
Depending on how educational you want to get, you can actually show the principle by pouring a cup of flour over two cups of cornmeal in a quart jar. Mark the height. Shake really well, then see how far down it went.