For kids--and adults- I would recommend using the circle drawing books made
for kids. That is t he BEST approach for understanding how the figure
operates--in circular connections. The axis line that usually defines the
spine, in conjunction to the ribs and the hips is necessary to understand
proper movement. Those are the first things I draw. Also use
proportions--typical human is anywhere from 6 1/2 to 8 heads long (breast
line, navel, pubic bone, upper knee, shin, foot).
Another idea I have to bring in art history/ appreciation is to draw on
tracing paper over some master's work using the above tools.
Also try pressurization for the line work that contours the body--really adds
to the movement.