He is a very young kid. He expects to come to a Tae kwon Do class and learn to do kicks, because that is what, in his mind, tkd is about. Honestly prospective students need there own separate thing, duck walking and other conditioning is not what is called for in the intro class. Showing and teaching him a sampling of the very thing he came to try out is what is needed. His expectations were not met, because he is a kid, he expected to kick, and do kick like things repeatedly. Not duck walk or plank. (I hate planks)
What the real lesson here is, their needs to be a intro class, were the gist of tkd is shown, and some basic things taught to them that give the right impression of what tkd is.
Had there been a properly structured intro class, we would not have this thread.