Scholastic's American Adventures series

For D's history, I did go ahead and simplify - it was so hard, I really am impressed with the history book I had - Glencoe-McGraw Hill American History - The Modern Era Since 1865. I like the setup, I like the way it has connections to other subjects: artists from the time making statements with their works about the then-current sociopolitical situations; scientific understanding of the time and how it influenced life; learning summarizing skills using important speeches and literary works of the time; lots more. Oh, well, as informative and interesting as the text is, it's way above D's ability to follow.

We are now using the last two books of a series of four that I suspected may have been intended for adult foreign learners of English. It isn't though, it's a Scholastic Inc. book and the phrasing of the preface sounds like it's written to kids. I have no idea what level it is but it's working very well for D. He understands what he reads, remembers and knows how it connects to the previous chapter, looks ahead to the next chapter at times to see what result comes about from what just happened, and even understands the sites I find on the computer that gives more of the details on what he just read.
This is an old series called American Adventures (not to be confused with the historical fiction series I bought that he doesn't want to read). I only have him write the answer to one of the chapter questions, mostly we discuss what we're reading (I read it aloud to him). He can actually discuss it! As much as we would like for him to just "get the credits", I can't handle marking it done when he has no clue. Neither do I want to leave him thinking he's not smart enough to understand something when he just needs it presented a different way. So we've found something that works!