Increase Mental Math with your students. Suggestion from commenter: This is one of my all time favorite activities to do while waiting in line. It keeps the kids calm and quiet and sneaks in mental math practice!
Great trick for teaching how to make Students use a highlighter to find the and then circle the other number with a crayon. Although, I think it would be easier to always make 10 with the larger number, not necessarily the first number in the equation.