I think, in general, it is the parents' role to provide opportunities to their kids and then to follow their child's lead. If your son is interested in these books then he is certainly getting something out of them. There is no way he would be spending his time on something out of which he got nothing. He may be understanding the majority of the text or just some of the text or maybe even just a little of the text but a lot from the pictures. I would think that all you need to do to support him would be to ask him how he's liking his book, what he's learning about, and if there's anything he's having trouble understanding, but all in a friendly conversational tone. I would think that, whatever he is getting out of the books now, it would certainly make him feel more comfortable with the material and familiar with the basics so that when he encounters the information later, it could only help. It sounds to me like you're doing exactly what you should be doing and that you're a loving, supportive parent!
