A children's book series that is criminally underrated is the Mercy Watson books. They're about 3rd grade level "chapter" books and they're hilarious. There's not really a clear message generally, but they're great at introducing some big words like "porcine" and "unmentionable". They're also great at introducing some tricky letter combos like in "toast", "Eugenia", and "Francine Poulet". Toast, porcine and Eugenia are in every book so it gives regular practice for those words. I also like that the big new word in each book (like "unmentionable") is used multiple times throughout the book to practice.
They're roughly 70 pages with lots of pictures and Little Man sits through the whole book.










