I put together a simple VI with a picture indicator and some joystick functions, so that by pushing the joystick the students could make a circle move around within the picture indicator. I then asked them to modify that VI so that things would happen when they push buttons on the joystick - for example, fill that circle with a color. Then make it a toggle, to see the difference versus having it happen only when the button is held down. Use the joystick throttle to make the circle grow and shrink. If your joystick has a rotation axis, simulate an omni-directional drive by changing the shape to a rectangle and then rotating it with the rotation axis. Depending on how advanced your students are, there are all sorts of options - add some momentum so that the circle slides to a stop when the joystick is released. Limit the travel to the edges (or make it bounce at the borders). Add a second ball that moves randomly - first in one axis, then across the entire area. Use the PID functions to have the first ball follow the randomly-moving one. There are all sorts of options that don't require a working robot.
