I loved the pictures! My favorite picture in this book has to be when Frank snot rockets on some kids locker. It is totally gross but so funny! This story is age appropriate and can be used in most grades K-9th. If you wanted to adapt it to use it in higher grades you could, just use different activities to enhance the point of the book.
If I were to use it in a classroom I would read the book, discuss bullying, and finally have them create their own book about a time when they were bullied. People of all ages love to draw, even if they say they do not - trust me. For some students it would be difficult to get their experience out , but telling people about it could mean healing from it. The story follows a child from getting picked on, learning how to start up for himself, and finally standing up to the bully to protect another. A part of the book I was unsure of, it had the main character state if it came down to it he would hit Frank, which would be totally against any bully curriculum I have taught. I would probably have a discussion on if hitting back was the right thing to do or not. Overall it is a cute book that you can use to discuss bullying and how to overcome it. I've included this in various curriculum packets dealing with making friends and standing up for yourself.