I was fortunate enough to have had some pretty good teachers, starting with a science teacher in sixth grade.
His hobby was inflating balloons with natural gas from the science room, tying pre-addressed postcards to them, and releasing them to see how far they could travel.
During the demo, we naturally wanted to learn more about the natural gas. The teacher demonstrated how the gas was flammable by holding a match to the bottom of the balloon he was holding.
You should describe this act to your friend and see if he can anticipate the outcome. The balloon failed at the bottom, releasing the flammable gas. The collapsing balloon accelerated the gas past the match, then the teacher's hand, and then the teacher's arm. The sheet of flame burned all the hair off the teacher's arm. We learned a lot that day. Science is fun.
You should describe this act to your friend and see if he can anticipate the outcome. The balloon failed at the bottom, releasing the flammable gas. The collapsing balloon accelerated the gas past the match, then the teacher's hand, and then the teacher's arm. The sheet of flame burned all the hair off the teacher's arm. We learned a lot that day. Science is fun.
Too funny. Can just picture that. I know just who I will ask to hold the balloon. He's got zero sense of humor. That in and of itself will be humorous. If chemistry labs were about blowing things up, I am sure boys would pay more attention.