For this activity students will need an ipad, tablet, smart phone or other device with a QR code application downloaded. You can find many free QR code apps in the app store for your device.
With this activity students will walk around the room in search of the answer to the number sentence that the previous card showed through the QR code. All number sentences subtract 10, 20, 30, etc. from a two digit number. My students love these activities! I use them as a center choice during math time.
I am going to continue to work on creating QR code scavenger hunts aimed at second grade standards. Check back often!