2-Digit Addition with first graders = tough stuff. My class needs so much practice on this. That is why I created this self-checking activity. This is great to laminate and put in math centers or during independent work time. Students can self-check their answer and get immediate results. Once you add the QR codes/ technology, you have them hooked! If you and your students loved this free sample, try the full version with twice the amount of cards.