Teaching the adults about oncoming force is easy – you just make them punch each other. Teaching the kids about oncoming force is easy – you just make them push each other. It’s a small but important difference.
Why is it a small difference? Because the vector of force between a open hand pushing slow and a punch pushing slow are just about the same thing. Why is it an important difference? Because the implied meaning behind pushing someone and punching someone (even slow and in the context of a controlled drill in a martial arts class) is huge.
So the students spend today’s kids class pushing back and forth at one another, seeing how they could take a hit (push), keep strong posture and be ready to return a good hit (push).