I use this as an activity to begin the Order of Operations Unit (5.OA.1) or as a review station throughout the unit. This activity allows students to figure out which answer matches the order of operations card. I have added incorrect answers if students solve addition before subtraction and multiplication before division. I see this all of the time in 5th grade! Also, the answer key spells a word backwards for an easy check.
Differentiation: If students are below grade level or need extra support, then I would only give them the correct answer cards and work out a few as a class.
If students are above grade level, I would give them some of the order of operation cards and all of the answers, but make them create the expression for some of the answers.