The snot-spattered experiments that show how far sneezes really spread...
Show little kids the images from about 2:20 to 2:30. Best ever preventative medicine.
Very good ;)
And a few pictures for coloring the droplets. Present the pages as way to count, mixing verbal with visual. Or alertnate colors to form patterns. Make it light, have fun with it (you know a whammy's coming). Let the kids decide which colors; give them a choice between two patterns. Or do whatever dot-to-dot they can come up with. Play a guessing game of the source as everyone busies about. Whole thing should only take a couple of minutes.... and then show them.
It's pretty convincing as is.