We let our son fill in the ends of sentences. He picks up on them surprisingly fast. I think when he wants to read a book over and over he's trying to memorize

We let our son fill in the ends of sentences. He picks up on them surprisingly fast. I think when he wants to read a book over and over he's trying to memorize it. The benefit of this approach ("hack"?) is that over time he gradually takes over more and more of the "reading", lessening the weariness of the reader!