If one includes incorrect answers, each of these problems will have more than one answer. In particular, tasks with multiple solution methods and multiple correct answers such as the one shown in Figure 3 are sometimes referred to as open-ended tasks [Becker and Shimada 1997 /1977]. Depending on what the children have
already learned, the diversity itself changes. If the children have only learned that the unit square is 1 cm2, then Task 1 has various solutions.