The"reading course" (by Dr. Fred Ray Lybrand) is just so clever.
It contains many simple ideas, but it's gold! It works in with the RC books at absolutely any level, or any well-written books, using whole books or just a page. It's delivered as video lessons for the parent to learn the ideas, and/or the children can directly listen.
From the first levels, it gives clever ways to think and ask questions about stories that are actually really fun to do. We get better at it by doing, and enjoy going on to the higher level ideas. No hurry, though! It's a way of thinking about stories and passages; nothing like a rote workbook that hurts enjoying the book. You know how sometimes analysis can kill a good story? This does the opposite, and actually makes you MORE interested in it.