My circular motion lesson plan called for 3 demonstrations and one inquiry activity. I started off with a quick demo and an informal pre-assessment. 12 out of 15 students surveyed did not know the word centripetal. 10 did not know any of Newton's laws of motion.
After playing with balls in a hoop, rotating water jars, and swinging paper cups on a string, they could all explain the forces at work in circular motion. Students formed a basic understanding of the relation of radius and period to centripetal force. Some groups asked about pendulums and so we made a side trip into the effect of a pendulum's length on it's period. We even calculated the speed of our 'astronaut' in miles per hour. A whopping 14 mph!
Not bad for 75 minutes.
But sometimes I can't think of that perfect demonstration. Or need a quick lesson filler. Or I need a visual 'hook' but don't have the materials. What to do? How about a quick video search?
YouTube is a good place to start. Search for 'centripetal force demonstration' or whatever. And get some great ideas for your next lesson. If your district blocks YouTube, then just download the video at home and bring it to work. Or ssh into... I better stop there. ;-)