Below is a video I saw at a workshop last year that gave me the idea of using QR codes in our library. The video shows some of the ways McGuffey HS used QR codes, not just in their library, but in several subject areas - family & consumer sciences, foreign languages, music, science, social studies and more. Maybe it will give you some ideas too! (This is a YouTube video, so you won't be able to watch it in school.)
Also, I have a collection of links with information regarding QR codes. Click here if you want to explore more on QR codes.