The ability to estimate is not only a valuable math skill but also an essential life skill. Many adults use estimation daily: when tipping a waitress, determining the cost of a sale item, or converting units. Within mathematics, the ability to estimate is linked to deep understanding of place value, mathematical operations, and general number sense (Beishuizen, van Putten, and van Mulken 1997) and allows students to check the reasonableness of their answers to mathematics problems in a variety of contexts.
Jon R. Star, jon_star@harvard.edu, is a former middle school and high school mathematics teacher and is currently an assistant professor at the Harvard University Graduate School of Education in Cambridge, Massachusetts. He is interested in the learning and teaching of mathematics at all grade levels.