There are 121 students at Sarah's school. Sixty-six of them are girls. How many are boys? |
 (enlarge) |
Student: One hundred and twenty-one minus sixty is sixty-one. Sixty-one minus six is fifty-five. |
|
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. |
|