Using a stick of ten cubes as a referent, children estimate how many cubes long a work table is, for example. See figure 5.2 . 5.3 Children also should be taught specific strategies to aid them in computational estimation. It is useful to discuss various strategies and to help students develop their own strategies. Continual emphasis on computational estimation helps children develop creative and flexible thought processes and fosters in them a sense of mathematical power.
Estimation is especially important when children use calculators.
This rough estimate provides children with enough information to decide whether the correct keys were pressed and whether the calculator result is reasonable. Such uses of estimation reduce the incidence of errors with calculators, decrease the mindless use of calculators for computation, and contribute to children's development of number and operation sense. Children often find that estimation skills are useful in their daily lives. Many children know when it is appropriate to estimate and how close an estimate should be, as the following anecdote indicates. Three children huddled together in a shopping mall, discussing the purchase of some clothing.