A good example that shows that air is really "stuff" is the way a parachute works. After doing the activity, think of the problems a parachute would have if air really was just empty nothingness. Work ...

and again with a parachute made of different material. Which design had the most air resistance, and therefore slowed the students the most as they ran? This experiment could be recorded as a ...

Parachutes increase air resistance and enable sky divers to ... Adjust your shapes to make them more hydrodynamic and redo the experiment. How did the changes you made reduce drag?