How Do You Teach Rounding?
To teach rounding I take several approaches.
The first method I use is to teach rounding with a sentence strip number line. I have students build a number line on sentence strips with whatever numbers we are working on. If they are working on the nearest 1,000 and nearest 10,000 for example, I may double side the number line sentence strip. If we are working on nearest 10 and 100 then I would double side the sentence strip counting by those two numbers. Here is how I have students build their sentence strip without much fuss.
First, I have them put a finger space down with one finger and make a mark. We put a zero here. I also have them leave a finger space before the end. They put the last number here such as 10,000 in this case since we were rounding to the nearest thousand.
Then, I have them fold the strip in half so that students can at least find a mid point. They put a mark at the mid point.
I have them put four fingers down to hold the space to make the next mark. Students repeat this four finger spacing until they get to the midpoint and then repeat the four finger spacing after the midpoint. This gets a fairly even number line if students do this. IT ISN’T Perfect, but it’s close enough to reasonable spaces give or take the size of the students hands.
Next, students label the numbers underneath the marks.
This will give students the numbers they need to use when making a number line sketch such as in the rounding roller coaster model I like to use. Before actually talking about rounding. I like to pose a number such as 8,456 and ask students where this number would fall on the number line. I have them place their finger where they think the number would go and I do a quick sweep around the room to look for understanding.
Here is how you can progress to the rounding roller coaster. Whichever numbers the students’ fingers are pointing between on the number strip go on the end of their roller coaster. For example with 8,456. The numbers would be 8,000 and 9,000.
Next, have students put the midpoint number in between the numbers on the two ends of the roller coaster. Then have them put a dot where the number they are rounding actually is. Explain that when a roller coaster is on top of the hill at the midpoint it will coast all the way to the end. If the roller coaster isn’t all the way at the midpoint then it will coast back down to the beginning. Whichever side it coasts to is the answer.
Now of course in the midst of all this, I have students learn the rhyme “4 or less let it rest, 5 or more raise the score” so that students have another rounding strategy to fall back on.
Now the rhyme and the roller coaster I cannot take credit for. I either learned it on the internet somewhere or from another teacher. I can’t remember, but both of these strategies support students’ understanding. These are my preferred ways of teaching rounding. Now, of course you will have students who don’t understand the above because they cannot count that high or have understanding of numbers that high. That is when I give them some counting practice using these number charts:
This is free in my TPT store:
And you can get these which count to larger numbers and they cost $4:
Or these count by smaller numbers up to 1,200 and are $7. I use these a lot with kids at school. They are great for up to grade 3 or as an intervention for older kids.
Now here is what I do with students who are seriously struggling. I don’t like teaching rounding this way because it really takes the number sense out of what they are doing, but some students just need to know how to get the right answer and do not have the number sense to build on to be able to round with understanding.
I showed the method above to a group of 5 struggling learners and all were really getting correct answers by the end except a resource student. Being able to write something down on their paper before they did much thinking really helped the students. To know that they could go ahead and fill in the zeros and fill in the beginning really helped them. However, like I said this isn’t the best way to teach for understanding.