Teaching children how to estimate properly is something I need to improve on.
As Jo Boaler points out in The Elephant in the Classroom:
“When an official report in the UK was commissioned to examine the mathematics needed in the workplace the reviewers found that estimation was the most useful activity. Yet when children who have experienced traditional maths classes are asked to estimate they are often completely flummoxed and try to work out exact answers then round them off to look like an estimate. This is because they have not developed a good feel for numbers, which would allow them to estimate instead of calculate, and also because they have learned, wrongly, that mathematics is all about precision, not about making estimates or guesses. Yet both are at the heart of mathematical problem solving.”