Mark Rober (the Glitter bomb package theft guy) started a Physics class today on Youtube. According to Youtube numbers, 70K people were watching it at the beginning and 377K had watched it when it was over. I watched it with my daughter and it was review for both of us, but it also was very, very good. https://youtu.be/pPn-Bay_ANU
FWIW, here are my favorite heavy gas videos: https://www.youtube.com/watch?v=ckaJs_u2U_A , https://www.youtube.com/watch?time_continue=30&v=drBjDy96iNI , and an image to help with "but how can things float on something you can't see" https://www.flickr.com/photos/10192726@N00/1367178603 . One can also play with layered drinks https://www.youtube.com/watch?v=sVsMmCb3Cdw . Self-layering latte is nifty, but harder to explain and make: https://www.nytimes.com/2017/12/12/science/lattes-layers-cof... , https://www.nature.com/articles/s41467-017-01852-2 FWIW.