QR Codes are a fun way of sharing/revealing information to students (and staff).
I have seen this used a lot with iPods and iPads in the classroom and today I was reflecting on the use within MacBook classroom.
A handy free app can be downloaded from here (QR Journal). This app uses the inbuilt camera to read QR Codes or you can copy and paste QR images like the ones below into the app.
To create QR codes I typically use GOQR.me
Have fun exploring the possibilities :)