Split your class into teams of 4
Students complete 6 throws (from the same position, same distance from the net, same height of hands) and record 6 slow-motion videos of those throws.
Review the concept of ratios and calculate the ratio between the real person and the person as seen on the video recording (measure the height of the person and the height of the initial position of the ball in hands).
Sketch each Parabola on the graph-paper or a whiteboard and state a corresponding equation in vertex form.
State which one of the trajectories will always get the ball in the net.