Why is Rounding So Important?
If you live in a state that uses math common core standards (3.NBT.1) or some variation, students are expected to know how to round whole numbers to the nearest 10 and 100, by the end of 3rd grade.
Even though rounding is a standard, I often feel like rounding is a “stepchild” math concept. Sometimes we like to focus on the major players (ex. addition, subtraction, multiplication, division), and this very important skill gets put on the back burner. I have been guilty too!
When students have a good grasp of rounding, they are capable of making reasonable estimates. Rounding and estimating are very useful in real life situations. We use them to see if we have enough money when shopping or when trying to get somewhere on time.
But My Students Know That Rounding Rhyme
Over the years I used different strategies to teach rounding. For example, I used the saying, “Five or higher add one more. Four or less let it rest.” I really enjoyed using that as a technique to round but then realized that my students really did not understand when or how to apply it. After some research, I realized the importance of teaching rounding in a conceptual way.
Then What Can I Do?
Great question! There are many ways to teach rounding in a conceptual manner. You can use interactive number lines, engaging games, open-ended questions, and provide ample time for independent practice. Read below for more details.
In order to get the most out of this activity, make sure that your students are able to verbally express how they rounded. I like to provide a sentence frame that students must use when speaking to one another. ( ___ rounds to ___ because it is ___ numbers away from ___ )
It is also a good idea to have students go all the way through the number line and record their findings. See photo below.
If you follow my blog then you know by now that I love using games to teach math concepts. Games are a great way to keep students engaged and promote learning at the same time. I choose two games that my kids loved to play and made 2 versions of each (Rounding to the nearest 10, Rounding to the nearest 100).
The first game is Rounding Face Off. Students play against each other by simultaneously drawing a card from their separate piles and quickly matching it to a game board. The player that makes the first correct match wins the round.
What better way to see if kids really understand a topic than to ask open-ended questions? I have found that when my kids have written responses to these types of questions I can easily see who “got” it and who did not. More importantly I can see if there are any misconceptions.
One way is to ask students questions when they are using an open number line. For example, you can ask students to respond to questions like:
What patterns did you notice?
Explain how you got your answer.
Is the following true or false? How do you know?
Students need lots and lots of practice! Practice should include different ways to solve problems. I like to use different models and question types, so that students can visualize and explain their thinking in a variety of ways. When you are teaching rounding, it is also important to give problems that include 2 and 3 digit numbers that round to the nearest 10 or 100. Here are some examples of the different question types that are included in this activity packet.
Scaffold teaching the concept of rounding by using a number line and sentence frame. Students practice with a partner by rolling number cubes to get a random number and then use a sentence frame to help them explain their answers
If you would like the activities used in this blog post, check it out here!
Greg Coleman, also known as Mr Elementary Math, has been an educator since 2003. In addition, he has served as an elementary Math Instructional Coach since 2010. He loves supporting Kindergarten through 5th grade teachers in providing great math instruction. Be sure to check Greg out on TpT, Facebook, and Pinterest.