Rounding

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Archive : 2001 : November : 7

Rounding
By Robin

I teach 3rd grade - and rounding has been a challenge to many in the class - for several years. I think some of it might have to do with development...only because one day, kids don't get it...and then (as I say) some fairy
sprinkled rounding dust on them one night and "poof!" - they understand it.
I teach by using a number line...but instead of it being a line, I make it a bridge. When I hit 5 or 50, I erase the spot where that number is. If the number you're rounding to has a 5 or 50, there's a hole in the bridge/number line so that they can't go back...they have to move up to the next ten or hundred.

This works really well b/c they can "see" that they can't move back.

As far as helping the students remember what to round to (nearest hundred/nearest ten), I have them underline the number they are rounding to...and teach it by doing 00 or 0. I make those 0's happy faces. If you're rounding to the nearest hundred, you will have TWO happy faces...if you're rounding to the nearest tenth, you will only have one face looking back at you.

For those who REALLY struggle, I make them look at the problem before they do anything. If they round to the nearest hundred, I make them put a _00. If they round to the nearest ten, I make them put a _0. If they have a number that's in the hundreds but it's rounded to the nearest tenth, I make them choose...for example, if the number you're rounding is 476, I make them draw their bridge number line and figure out what they could round to... on the far left of the number line, they'd have 470, on the far right, they'd have 480. So, next to that problem, they'd write _ _0 for rounding.
THEN, I have them go back and do the bridge idea after they'd figured if the rounded answer will end with one 0 or two 0's. This helps them break it down, step by step, so they don't get too confused.
Again, my best advice is not to overkill the rounding. I did last year, and I got frustrated when they wouldn't get it. Revisit it every few weeks...again, that fairy dust comes out of nowhere...all of the sudden, they just get it. Plus, you don't get frustrated and bored.

If she's a "physical" learner, have her do the number line on the floor using masking tape. Then, write the numbers on it...and tear out the space where the 50 or 5 would go. She could see that you cannot go past the broken bridge...so you have to go the other way.

Let me know if this helps... I know it helped my kids this year - a lot. Thanks and good luck!