My son’s first grade class has a recurring parent “mystery scientist”. Tuesday is my turn. I have 30-45 minutes to do something funinvolving science with the class. I’m not sure what the other parent’s have done. Any ideas?
Thanks in advance.
Make a hot air balloon out of a paper bag?
Show how a diving bell works?
Baking soda and vinegar volcano?
Make a lemon clock.
Make a hybrid lemon-human clock.
Do the penny in 2 forks balanced on a glass rim trick to demonstrate counteracting forces.
Soda bottle tornados.
Demonstration of Lenz’s Law slowing the fall of a magnet through a copper pipe.. It looks like magic, but can be explained in concept pretty easil, and can be put together for about $20. You can drill holes in the tube to see the magnet falling so long as they are evenly spaced and don’t remove too much material. You don’t need a spherical magnet (which may be difficult to find locally) but it does have to be a rare earth (usually neodynium) magnet to set up sufficiently strong eddy currents. Best of all, it is a display of relativity, although the reason why is probably beyond the ability of first graders to understand.
Stranger
Here’s a site with filterable activities - choosing first grade and science yields a bunch.
It’s too bad the capillary action in celery takes so long, but there are some fairly quick ones.
I love the surface-tension powered soap boats:
http://www.funscienceforgirls.com/2011/03/mini-monday-surface-tension-soap-boat.html
All your needs can be purchased here–
http://www.sciplus.com/s/c_19/sf_176
If you can’t get a science project lesson out of this…
I always used to bring liquid nitrogen to school, but I work at a place with ready access to it.
A really simple but great experiment involves having two empty soda cans resting on a bunch of straight drinking straws. Use another straw to blow inbetween the two cans that are an inch or two apart. Ask the students to predict what they think will happen when you blow in between them. Then ask them to come up with a hypothesis to explain what actually happens, and why their original prediction was wrong or right.
Prince Rupert’s drop
Save this video on your iPad or laptop, and show it to the class. Read up on it first so you can explain it, and field questions.
For obvious reasons, point out that it would not be safe for an classroom demonstration (exploding glass)
Make advance arrangements for the school to allow you to use a large monitor to show the entire class the video.
Plan B
Bring a loaded .40 calibre gun to school, and a bucket of water, frozen to smooth ice. Shoot a bullet into the ice at a precise 42 degree angle. Note the amazing results.
This phenom was actually proven on myth busters. Maybe some physics major dopers can explain this, like why isn’t the bullet deformed?
You can even slide a magnet down an angled copper sheet for this effect.
Yep, no one could possibly object to this. 
Vivisection.
First, get some chlorine trifluoride…