How to Teach Rounding

Rounding numbers is taught in third, fourth, and fifth grade classrooms across the United States. This blog post is packed with helpful information that will give you the foundation you need to plan and deliver effective math instruction. Read below to learn more!

This blog post will...
  • explain why it's important for you to teach rounding
  • identify the key understandings of rounding numbers for third, fourth, and fifth grade students
  • list the most common misconceptions students have related to rounding, so you can address them proactively

You should always provide your students with a purpose for learning. This can be done by explaining to them why rounding numbers is important and giving them examples of how we use rounding in the real world.

Rounding is a way of simplifying a number so that it is easier to work with. The new value should be close to the original value. Rounding can be used in mathematical situations where it is appropriate to estimate. It is important because it helps children comprehend the power of estimation, which has many real-life applications.

Relating the concept to your students’ own real-life experiences makes their work more interesting and meaningful. Real world examples of rounding include rounding the cost of snacks at the grocery store to the nearest dollar to estimate their total cost to see if we have enough money to buy all of them, estimating about how many miles we are going to travel during our family road trip this summer, or finding about how many water bottles are needed for the campers at camp if the water bottles come in boxes of ten. I encourage you to create a rounding numbers anchor chart with your students and record these examples and more.

Essential understandings, also known as enduring understandings, are the big ideas we want our students to master. They help you focus your teaching on what you want your students to know, understand, and do. These “big ideas” derive from standards and serve as the foundation for designing all of your rounding numbers lessons and activities. 

In third grade, students should be able to...
  • assess the reasonableness of answers using mental computation and estimation strategies including rounding.
  • round whole numbers to the nearest 10 or 100.

In fourth grade, students should be able to...
  • assess the reasonableness of answers using mental computation and estimation strategies including rounding.
  • round multi-digit whole numbers to any place.

In fifth grade, students should be able to...
  • round decimals to any place.
  • use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers.

  • In order to effectively teach your students about rounding and estimating you must anticipate, identify, and correct and misconceptions or misunderstandings they have developed. To help you, I have listed some of the most common rounding misconceptions your students are likely to make. 
  • The student rounds down instead of up when 5 is in the place that is followed by the number he or she is rounding. (Example: A child rounds 45 to 40 when asked to round to the nearest 10.)
  • The student misuses the rule for rounding down by decreasing the value too much. (Example: A child thinks rounding 82 to the nearest 10 is 70.)
  • The student thinks rounding is a synonym for guessing. (Example: A child rounds 33 to 50 when asked to round to the nearest 10.)
  • The student thinks rounding to the nearest ten means replacing the digit in the one's place with a zero. (Example: A child rounds 98 to 90.)
  • The student misuses the rule for rounding up by changing the digit in the elected place while leaving the other digits in smaller places as they are. (A child rounds 5,654 to 5,754 when asked to round the nearest hundred.)

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