Rounding is one of those concepts that seems so simple but always blows my kids minds! There are a bunch of different rhymes that students can memorize but in the end I want my kids to understand rounding not just follow a memorized procedure.
These are my two favorite:
1, 2, 3, 4
Round down to the ten (hundred) before
5, 6, 7, 8, 9
Round up on the line
Find your place
Look next door
5 or higher
Add one more!
To build number sense and make sure my students really understand rounding, I started having them write the tens (or hundreds) on either side and circle the closer ten (or hundred.) This confused them a little at first but by the second day they were pros. I had the kids use dice to roll 2 or 3 numbers and then round to the nearest ten. After about 10 minutes we switched and they rolled 3 numbers and rounded to the nearest hundred. Here are some pictures of their work. (We often write on our desks with dry-erase markers.)
Afterwards the kids had to write in their math journals and explain rounding in their own words. It was interesting to see how they made sense of it. Some used the rhyme, some used logic, and some referred back to our “car on a hill” visual from the first day. (The car is about to run out of gas. If it’s exactly in the middle of 2 gas stations should it turn around and go back or just keep moving forward?)
Happy rounding! 😉 Kady
