I have a tutorial for this bag over on Sew Mama Sew today! Here is the link. In answer to some of the comments I am getting, the apple print and blue floral are both from the Farmdale line from Alexander Henry. I found some of the apples fabric here at Hip Fabric.
My daughter has already been using this bag and it is working just as I hoped it would. She usually misplaces her tally sheet by the first week of summer reading and it is in the pocket of her bag still! She has also been keeping the receipts she gets that list all the books she has checked out all folded up in her library card pocket with her card so that is helpful too. Let me know if you make one, I would love to see it!