Only problem being there is a distinct lack of examples out there on the net unless you are willing to pay for it.
|example of math and QR codes - juniors|
What's great about the problem solving activities part of these QR Codes [not the ones above] is that it is instantly fun for students because of the act of scanning...it creates collaboration in the groups.
Their own QR Codes can be made with their solutions and then a fun Gallery walk entails followed by discussion.
It does require lots of devices - BUT I did discover that software can be added to laptops so their webcams can be used as the scanners [that was news to me]
Macs use QR Journal
PC's use quickmark.com