I give private art lessons in my home. For children age 4 through maybe
8, Mona Brookes' approach is quite good. I also teach high school, and there
I use Betty Edwards' Drawing on the Right approach, so I know I mix both in
my work with the children. The idea Brookes uses helps slow children down in
their drawing, looking for the curves, angles, etc. in the objects they
observe. It makes detailed subjects more manageable for them by helping them
see it in parts. I have never used Brookes' approach in a classroom, so
don't know how it would work with a larger group.
Borrowing the book from the library first seems sensible to me.