I agree VDJ.Classes with mostly children is a sure sign that the meat of the training is probably fairly soft.
I remember back when I trained in TKD we only sparred hard in the late adult class. The early class was more of a glorified baby setting session.There was a definite difference in the approach of our instructer between the two classes.Even as it was the adult class didn't work on the self-defense aspects of the art very often.While our focus wasn't olympic TKD(don't get me started) the fighting we did was of the sparring variety only.Self-defense was basically not a high priority.