This product is a hands on approach to practice subtraction facts. It incorporates the use of a number line and technology using QR codes. Students love using QR codes and this allows for independent learning, however, these are optional. Print on card stock, laminate, and students can either write on them with dry erase markers or they can write their equations in a spiral. There are 36 cards and an answer key if you don't have a QR code reader.(ipad, android phone, iphone) QR code reader apps are usually free. This product compliments my Missing Addends with Number Lines and QR Codes that you can find in my store as well.