Liquid nitrogen is used to visualize the aerosol particles emitted while speaking, coughing, breathing, and sneezing. The ability of various masks to block these droplets was also tested.
The June, 2018 issue of the Journal of Chemical Education contains an article that describes a simple, yet fascinating experiment that you and your students are going to love! It involves the use of butterfly wings from the genus Morpho. I obtained some of these wings and enjoyed experimenting with them. You will too!