John is picking apples. He picks 36 from the first tree, 18 from the second tree, and 27 from the third tree. How many apples does he pick from the three trees altogether? |
 (enlarge) |
Student: Eighteen plus twenty-seven equals forty-five. Forty-five plus thirty-six equals eighty-one. |
|
Students at the Advanced Additive stage are learning to choose appropriately from a repertoire of part-whole strategies. They see numbers as whole units in themselves but also understand that “nested” within these units is a range of possibilities for subdivision and recombining. |
|