1. Ask the students to predict whether a ball thrown horizontally or dropped vertically will hit the ground first. They usually know both will hit the ground at the same time. Ask them why, since the ball thrown horizontally travels further. They can usually explain that horizontal and vertical motion are independent and that the vertical motion determines the falling time.
2. Bring students to the back of the room to play with the air table. Ask one to run the computer while the other pushes the puck along the x direction only. Acquire using Tracker or VideoPoint. Scale the movie and then locate the puck in each frame. Ask the students to sketch six graphs (no numbers, just the rough shape): position, velocity, and acceleration vs position for x motion and again for y motion. Then test the predictions as a class using the graphing capability in Tracker or VideoPoint. They usually have little trouble with this.
3. Repeat with the much more complicated motion shown here. Many will need some help, particularly with the acceleration.