The double circles represent the touching of each of the spots twice. For the number 7, one spot is touched once, and the three spots going down are touched twice. Each spot is touched twice for 8 and three times for 9. Make sure to teach the children to always start with the larger number when adding. 6 through 9 are rarely used for addition because they are usually the larger number and other fact strategies are more efficient.
Students place counters on the touch points of numbers.