Builds fluency in this common core skill of "writing expressions that record operations with numbers and with letters standing for numbers". ( CCS: 6.EE.2a). Your students have fun getting up and moving around the room. The complete directions, cards, student worksheet and key are all included.
Remember, "physical exercise puts the brain of the learners in the optimal position for them to learn." to quote Harvard Medical School's Professor John Ratey, in an 2008 Education Week article
The cards can work as task cards in a math center as well.
There's a theme for your students to enjoy.