I just wanted to add, I do this with my son, who doesn't have any reading difficulties, as well. Right now I'm reading Miss Peregrin's Home For Peculiar Children. I've noticed that he likes to stop periodically to ask questions, and I think it's partly asking how to discuss something he's thinking... what words to use, etc.
I didn't wait for DD to stop me to ask a question, though she was certainly welcome to at any time. I would preempt her with questions of my own, especially when the language got outside of her experience. "Do you know what that means?"
At various times I'd interject other questions, too, to gauge her understanding of the material, and get her thinking more deeply about it. "Why do you think this character did that?" "Do you think that was a good idea?" "What do you think will happen next?" Etc.
When we read HP, these options presented themselves: "How is this different than the movie?" "Which version of this event did you prefer?"
