Estimation is often overlooked in lessons involving multiplication or division. Even if students are told to estimate first, they often calculate to find the precise answer then round it to make an estimate.
That should prompt teachers to consider the purpose of estimation. Are we doing students a disservice if we bypass estimating before computing? According to industry leaders, estimation is the single most critical skill to apply in planning for land development, architectural and engineering design, and project cost development. Estimating the time it will take to complete a project is a critical skill. If we survey shoppers at the mall, how many will say they pause shopping to calculate the precise answer or estimate costs?
For elementary age students, estimation is a tool to monitor reasonableness of answers.
In the Common Core State Standards for Mathematical Practice, using appropriate tools strategically emphasizes students using estimation prior to computing. “Students detect possible errors by strategically using estimation and other mathematical knowledge.” Click here to learn more! Standards for Mathematical Practice
As you watch the following video, consider the following:
• How is estimation used as a strategy for solving division problems?
• How beneficial is it for students to use estimation as a strategy rather than only finding an estimate as answer?
• How can estimation and adjusting the quotient help when dividing with 2-digit divisors?
Video: Divide 4-digit dividends by 2-digit divisors by estimating and adjusting the quotient