The books have many great teaching ideas and a list of further resources. There are also free activities, resources, and lesson plans on the Core Knowledge website. It is a great site I have used it many times before.
I am not sure that I would even call these books textbooks. They are not boring. They are full of some of the greatest works that humankind has ever produced. There is not one paragraph of twaddle in the whole book. I love that the Math activities are all hands on. They make a great addition to every homeschool library. If you are not sure, go to your local library and check one out.