Rounding: Part 3 Teaching Rounding within 1000

This is the third in a series of posts that I have written on rounding. If you would like to catch up on the previous posts, you can read Why Teach Rounding? and Rounding Within 100 here.

In this post, I will look specifically on the next steps to teach rounding and outline what children find difficult.

Visuals

As with Rounding Within 100, visuals are key. Do not go straight to the procedural! Children may have learnt rounding last year and have not revisited it since. Secondly, rounding with 1000 differs slightly because children are asked to round to the nearest 100 and to the nearest 10. In my experience it is the latter that tends to pose more difficulties.

As I mentioned in my previous post, I use my rounding rulers for a number of reasons. The same applies here.

Lies Between

Rounding to the nearest 100

Take the number that you are planning to round, e.g., 342. To begin with, we will look at rounding it to the nearest 100. Ask children what the two bounding multiples of 100 are. Children should be able to easily tell that it lies between 300 and 400. When I use my rounding ruler, 350 is clearly marked as a midway point. I ask children which side it is on. When children place 342, they can clearly see it is nearer to 300.

Rounding to the nearest 10 within 1000

This is trickier for children. When asked to round 342 to the nearest 10, children will often answer 40. Asking children what the two bounding multiples of 10 are before rounding, can help to prevent this error. On the rounding rulers I use, children can see that it is between 340 and 350. Using this as a first step, allows children to really understand rounding to the nearest 10.

Try the same process with 968. What two multiples of 10 does it lie between? Once children, identify 960 and 970, they can see that 968 is closer to 970. Although the numbers are getting bigger, the rounding process has not changed. We are still asking the same questions: What two round numbers does it lie between? Which one is it closer to?

Scaffolds

I continue to use the rounding rulers, moving onto the blank ones when children have had some practice rounding. The blank rounding ruler requires children to move on a little bit, by requiring them to identify the bounding multiples themselves.

If you would like to use this approach in your own classroom, my Rounding Pack includes ready-to-teach slides, practice activities and the Rounding Rulers used throughout this series.

You can find the Rounding Pack in my TPT store here.