This is a math center that requires children to solve addition and subtraction problems before placing them on "less than 12", "greater than 12", or "equal to 12". They record their work on a recording sheet for assessment. I would place this game as 2nd semester of 1st grade or 1st semester of 2nd grade. Using number lines would be to the teacher's discretion. It could also serve as small group guided practice in a mini-lesson (K or 1).
*30 mixed addition/subtraction cards
*Student record sheet
*Answer sheet for quick checking