Look at them and notice how every drawing focuses heavily on the buttons on the shirts and coats. Plus the body sizes are very similar from drawing to drawing. This seems outside the level of probability for a sample of drawings this small. I highly suspect that all of the drawings were drawn by one adult trying to make it look like students drew them.
The children are about ten years old, right? So, despite their lack of skill in seeing, they have the dexterity to draw what they want to draw, and so you'd expect them to draw similar body sizes, in approximately the right proportion (except for the eyes which we tend to perceive as 1/3 of the way from the top, when in fact they are the midpoint.)
Why not go with the much simpler and much more likely explanation that the before and after pictures and descriptions all have similar content because the teacher held discussions before the students drew the pictures, and these discussions were lead in a certain direction.