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
How do you write on your desks? Are they covered in something special?
Nope, just regular desks. Dry-erase markers are magical! 🙂
I do the same thing, and the understanding seems to be a lot deeper of what rounding is, and why they are doing it. I have them draw a number line, from the ten or hundred before to the one after and then have them place it on the number line where it should go, and then it’s obvious which number it is closest to.P.S. My students write on their desks in markers. The first time I did it I was like, “Duh, why have I never done this before?!”
My students write on desks all the time. one reason is it takes away the rule of “don’t write on my desk or else…”, which eventually they will write on the desk anyway. And secondly, for some reason, everything seems to become so much easier when they write on the desk….
How do you get the dry erase markers off of the desks?
Hi Amy! I’ve done it many ways. I used to grab 20 tissues, rip them in half, and have a student pass them out. At one point, I’d collected all of my son’s old baby socks and given each student a sock to keep in their supply box. And then I saw this great idea to buy the cheap sponges at the Dollar Store, cut them into fourths, and give each student an “eraser” to keep in their desk. All 3 methods worked well! At the end of each week, I give 3 students a wet wipe and they go around and clean the desk tops more thoroughly.