I will post as many gems as I can from the American Association of Physics Teachers Summer Meeting held in Washington, DC July 28-August 1, 2018. On Twitter, that's #AAPTSM18. The items may be new or classic; simple or complex. Here's one such gem.
Dave Maiullo shows us his smoke ring cannon, adapted to the constraints of the room. Like most things, ring vortices look even better in slow motion.
Maiullo Smoke Rings
Bonus: Maiullo Dragon Voice!