Is your child in AAP (this is the AAP forum)? If so i wouldn't bother prepping, your kid ought to be able to handle them with ease.
They've always been pretty basic, as long as your kid is an average student even in gen ed, they ought to pass. Also, unless you're talking older kids who need the verified credits, at the elementary level I don't think failing one even has an impact on you (the school yes, but not the kid).