**Estimation strategies for number **

Throughout all the strands of the maths curriculum emphasis has been placed on the development of estimation strategies. Estimation is the process of taking an existing problem and changing it into a new form that is easier to compute mentally and gives an approximate answer. This skill is essential for real-life mathematics, for example shopping or measuring time and distances.

From the very early days at school children need to be encouraged to estimate. The young child finds it difficult to differentiate between ‘estimate’ and ‘answer’. The teacher will have to lead the work by encouraging them to make a sensible ‘guess’, to test their guess and revise it where needed. Estimation is a help towards finding a solution but need not in itself be the solution. This is important in measurement activities, where the children can be encouraged to compare objects as being ‘a good bit longer than …’ or ‘only a little heavier than …’

Children must also be taught to investigate the reasonableness of their results. They can be encouraged to develop their own ways of deciding when an answer is reasonable. They can be presented with a problem and several solutions, from which they select the most reasonable solution.

Estimation is also necessary for work with calculators so that the child can evaluate the validity of the result given by the machine. Quick recall of number facts and a strong number sense are important for efficient estimation. There are many different approaches to computational estimation, and good estimators use a variety of strategies.