Flinn Scientific has a kit of Halloween demos to get you started.

Hi there, My colleague does this demo every Halloween and she's the talk of the school: https://www.stevespanglerscience.com/lab/experiments/exploding-pumpkin/ It definitely takes some time to carve the pumpkins beforehand, but I think you can usually get at least 2 demos out of each pumpkin. Cheers!

These are great, Sherri! I found a great website that has a bunch of demos, with recipes and background chemistry: http://www1.chem.leeds.ac.uk/delights/texts/

Hi, I would love to share those things with you. I believe it would be best if you contact me at sherri.rukes@d128.org with your contact info and I can mail you a CD full of things to try.

Sherri, Is there a place where the directions for all of your demos are in "one place"? I'd love to hear your ideas for other holidays.

I do a wide variety of demos for Halloween.  I usually do about 25+ demos during the class period.  Here are some of them to give you some ideas: Burning dollar demo, puking pumpkin - elephants toothpaste in a pumpkin, yellow blue switch - a - roo demo, water to wine demo, tonic water under a UV light, decomposition of hydrogen peroxide in a painted black florence flask, instant light demo, putting glow sticks in hot and cold water, mystery messages with goldenrod paper, orange juice to strawberry float demo, firefly demo, 4 light oscillating reaction, phosphorescent paper and uv light, etc. This is just a start.  When I have some more time, I will list some more.  I do have a bunch more and even have demos for a bunch of different holidays and event that occur for high school kids.  Let me know if you would like to get more ideas or any other help.  Remember to practice any demo before you do it infant of your class, be safe and relax and have fun.