Do you have any stencils? I’m having kids trace a square, for example, then try to draw one that looks like it the same size. Here’s a good stencil set for cheap: General Purpose Junior http://www.dickblick.com/products/chartpak-pickett-arrows-and-shapes-templates/?wmcp=amazon&wmcid=feeds&wmckw=55476-1800
The best early step by step drawing book is The Big Green Drawing Book. http://www.amazon.com/Emberleys-Big-Green-Drawing-Book/dp/0316789763/ref=pd_sim_b_8 )