I was reading a book called 'Number the Stars'. It was written by Lois Lowry...It is interesting and easy to understand...

There's a children's literature section in Project Gutenberg. They are all free. https://www.gutenberg.org/wiki/Children%27s_Literature_(Bookshelf) . I recommend The Legend of Sleepy Hollow, Treasure Island, Jungle Book, and A Christmas Carol.

Try Cinderella or Snow White or even Sleeping Beauty.