This could be a fun science fair project someday :) Ants stomachs are transparent. a woman noticed it when ants drank/ate spilled milk one day so she gave them some colorful candy and then photographed them!
Ed Dancing raisins activities. Lots of fun experiments. I have done this experiment, and seen the entire class become silent out of curiosity. It is a great engagement piece for a lesson, and it can be hands on if you ask for volunteers!
Make a lung using a 2 liter bottle, balloons, some playdough, and straws. Then inflate and deflate the lung-balloons by pushing or pulling on the diaphragm balloon. I like the idea of using 2 balloons!