The Five Finger Rule

Do you know about the "five-finger rule?" Open the book to a middle page and have your child read that page. Whenever they come to a word they don't know, have them hold up a finger. If they are holding up five fingers before they finish reading that page, the book is too hard. If they don't hold up any fingers, the book is easy. If they hold up two or three fingers, the book is most likely a good level to help move them foward in their reading skills.

(from Wild About Reading)