Answer:
They can use counters or their fingers, but they can also use doubles facts. If they know 5 + 5 = 10, they know that the sum of 5 + 6 will be one more. Thus, 5 + 6 = 11. Practice solving other doubles-plus-one facts together, such as 3 + 4, 7 + 8, and 9 + 8.