Inertia with a glider (air track)
To demonstrate that since the glider is at rest, and there are no forces acting on it at the time, that it will remain at rest.
Place the air track on the rolling cart and make sure that is it level. Next add a glider to the track while the air is off. Move the rolling cart back and forth and the glider should stay on the same spot relative to the air track. Then start the air pump and move the rolling cart back and forth once again. This time the glider should stay in the same spot relative to the table the rolling cart is on at the time.
The easiest way to make sure the air track is level is to start the air pump and have a glider, with some weight on it, on the air track. Use weights or whatever else you think is necessary to elevate one of the sides of the air track as is necessary to level the air track. This may take some time so this may want to be done a few minutes before the class is to start.