These are classic literature books for the young. My children enjoy them and now that they are ready readers, I offer them simple quizzes, games or activities to do when they finish these books to see if they understand.
I have grouped the books by the recommended age for these books. However, your child can be reading them earlier or later. One of my sons read the all these by 10, and the other son can read the aged 8 books at 8. So to each his own. Don't be too worried. Just progress and keep the effort.
Start with a few pages and work to a few books a day.
Nice books to carry in the bag for them to bring to school for silent reading.
These books are also classics. Some schools use them as Literature books. My son loved all of them.
Books that somehow captured my kids' fantasies, my job was just to buy them and put them on the shelves.