Rounding numbers always seems to be a challenge for many of my students each year. When I approach how to teach rounding every year we create anchor charts, practice, and play games until they finally start to get it. I know from years of struggling with it that figuring out how to teach rounding isn’t easy, so I’m going to talk to you about a few of the activities we do to review rounding. I usually teach rounding with whole numbers, but the activities can easily be modified for teaching rounding decimals, too!
We create the anchor chart together and highlight the steps that we use to round ANY number. We color code examples so they match the steps. That made it easier for students to find which part of the example went with each step. My struggling students are able to access the poster as needed while those that don’t need it continue working. It’s especially helpful for my students with special accommodations as there are many steps they need to remember and this can sometimes be difficult for them.
After we go through the anchor chart I like to teach rounding on a number line. I give each student a blank, laminated number line and a dry erase marker. We started to practice with those. I would write a number on the board that they would need to round. They would write the benchmark numbers at either end of the number line and the midpoint in the middle. Then, they would plot their given number on their number line.
After, we would decide which number it was closest to. Then, we would notice the digit to the right of the place we were rounding to. Students would then circle their answers on the number line. We do a few of these together and then the students practice on their own to practice a few more. I think this activity really helped the students to visually see which end of the number line their number was closest to and what rounding actually is.
Human Number Line
I like to give students a set of cards (we usually start out with a set from 1-100 counting by 10s). I have masking tape down on the ground to create the number line and the students are the numbers. They quickly order themselves from least to greatest. After that, I chose one student to be the plotted number. I give them a whiteboard with a number written on it. They stand up and hold up their whiteboard. We then discuss between what two benchmark numbers they will most likely fall between and the students with those numbers will go up to our number line on the ground holding up their number cards.
Next, I chose one student to be the midpoint. I gave them a whiteboard and we discuss what number is the halfway distance. That student writes the number on a whiteboard and stands in the middle of the number line. The student that is the plotted number will be placed where they go on the number line and the rest of the class tries to determine which number the plotted number would round to.
After playing a few rounds of this activity, we begin to notice a pattern with the halfway distance markers. My students absolutely love this activity every single year and I will never quit teaching it this way.