Hi! I'm just sharing about our latest science lab. To show that air has mass, we filled a bucket with water (half full), stuffed some tissue into the bases of plastic cups, then held each cup by their bases and slowly immersed them (upside-down) into the water. We made sure not to lean the cups as they we being immersed. For the final step, we slowly pulled out the cups while keeping them in the upside-down position. With our other hands (which were dry) we reach into the cups to test the condition of the tissue. Can you guess if the tissue was wet or dry?
There are other experiments that you can do to show that air has mass. A simple one that I did with some younger students was to fill a balloon with water and fill another with air. I would ask the students to describe what is in each balloon. They would usually say that the second is empty. So I would challenge them to gently squeeze down the second balloon because since it is 'empty' then the balloon doesn't have to be so big. Then they realize that it has air and that they cannot make the air disappear. So then we talk about mass.
What kind of experiments do you do with your students to prove that air has mass or takes up space?