Students love QR codes because are fun, they get to use technology, and they can check their own work!
This pack has 24 cards that align to the third grade common core standard:
3.MD1. Tell and write time to the nearest minute and measure time intervals in minutes. Solve word problems involving addition and subtraction of time intervals in minutes.
You will need a device that can scan QR codes (iPad, smart phone, etc.). You can use the cards without it, but the students will not be able to check their work.