Reading Upside Down

I can't figure Maddie out. We are doing mommy summer homeschool and she's doing it more and more. She reads her books normally but when she reads the review word lists at the beginning and again at the end of the book she turns it at a minimum sideways and sometimes nearly completely upside down. I suppose as long as she's able to read it then I can let it go and give her a little wiggle room because sitting still long enough to read a book is hard to do still.