# Rounding to the nearest headache

Discussion in 'Elementary Education' started by sarypotter, Oct 23, 2009.

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Oct 23, 2009

Okay.

My third-graders are learning how to round to the nearest hundred.

Wait. Let me rephrase that. My third-graders are supposed to be learning how to round to the nearest hundred.

Two Mondays ago, we studied rounding to the nearest 10. We used a variety of hands-on strategies to accomplish this goal, and it was mastered fairly quickly by all students. (That isn’t as impressive as it might be, by the way; I’ve only got three third-graders.)

This past Monday, we started rounding to the nearest hundred.

They did fine. For the first few lessons.

I swear. They knew how to round to the nearest hundred when they left on Monday. And they knew how to round to the nearest hundred when they left on Tuesday.

But when they came back on Wednesday? It was GONE. As if we had never studied rounding before.

Today, it was even worse than that. Today, it was as if they had never even been to school before. They didn’t know how to put their names on their papers. They didn’t know which desk belonged to who. And they DID NOT know how to round to the nearest hundred.

I kept my patience … for a while.

I showed them how to narrow their choices down to two possibilities – the two multiples of hundred that are nearest to the number in question. When they didn’t seem to remember this concept, I made it even easier.

“The two choices,” I said, “are 600 and 700.”

“I know!” shouted Student A. “5,000!”

Just as Student B shouted, “27!”

“Guys,” I said, bewildered, “the answer is either 600 or 700. Those are the only two choices. The number you say either needs to be 600 or 700. So no other answer has even a chance of being correct. So … which is it? 600 or 700?”

“94!” shouted Student B.

“400!” shouted Student A.

Luckily the students left for lunch about that time, saving me from pulling out chunks of my own hair in frustration. They returned half an hour later, refreshed and ready to tackle rounding anew.

Yeah.

After fifteen minutes of rounding torture, I decided I’d better return to safer waters. I put a few two-digit numbers on the board and asked students to round them to the nearest 10. So imagine my surprise when the answers ranged in length from a single digit to six.

Defeated, I handed them their homework papers.

“What do we do?” Student B. asked.

“Circle the number that is in the hundreds place,” I instructed. “That way, when you come back on Monday, we’ll be ready for rounding.”

Student B. wrinkled his brow, looked me in the eye, and asked, “What’s rounding?”

You know what? I’m not sure even I know the answer to that question anymore.

Does anyone have any great strategies for getting rounding to stick?

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Oct 23, 2009

Here's how I teach it. I tell them that we're going to think of 0, 1, 2, 3, 4 as good guys, while 5, 6, 7, 8, 9 are bad guys.

I then relate this to movies they know. Good guys like you just the way you are, but bad guys are always trying to change you/trying to get you to be something you're not.

Then we take a number like 364. If we're rounding it to the nearest hundred, I tell them to underline the hundreds column. We call this our starting point.

Then we draw a little arrow that curves down from the line to the number next door (the 6). Then we draw little lines above the 6 as if it were lighting up (I can't describe it any other way). We call this our decision number. This number and this number alone will decide for us what we should do.

Then I ask them if 6 is a good guy or bad guy. Since it's a bad guy, it tells the 3 to change into a 4 (they know that the number always goes up by one) and then everything after the stating point changes to a zero.

You'd be amazed how well this works after a bit of practice. Of course there are special cases (999, etc.), but you can modify it when you get to that stuff.

If you have a number like 4,102 and you're rounding to the nearest ten or hundred, remind them that everything before the starting point stays the same (again, except for special case numbers).

I hope that was descriptive enough. I spent a few weeks on rounding last year with my third graders until I came across this method. They got it instantly.

Good luck!

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Oct 23, 2009

I think that 3rd graders still need to master this skill hands-on before they understand it abstractly (is that a word?). Use a base-ten set at first. Have them model the numbers and the hundreds/10s numbers to compare. After they have mastered this, then move on to using hundreds charts (yes, you might have to reduce them and print many of them). I really don't like having young students memorize the rules for rounding before actually understanding what it all means.

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Oct 23, 2009

The best rounding rhyme:
"Five or more, up the score. Four or less, let it rest"

6. ### EMonkeyConnoisseur

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Oct 23, 2009

One thing I did in the year I taught third grade is I gave them sheets of paper with the number and a line on either side. I started it with the two possible choices already on the lines and had them circle the correct rounding number, then they had to start writing in the two choices and circling the correct the correct number. It actually seemed to work pretty well.

7. ### noreenkCohort

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Oct 23, 2009

We use the "lasso" strategy. They have to underline the digit of the place value they are rounding to. Then they circle the number to the right to make a lasso (sometimes we get into a whole cowboy story if needed). We draw a little hill above a number line to show that they round to the next highest number if the digit is 5 or more, so they have to draw a little arrow next to the number showing if they should round up or down. Then the number inside the lasso and all the numbers to the right get "crushed" into zeros. The little details in our rounding story seem to help things stick with our special ed kids.

8. ### tgimHabitué

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Oct 23, 2009

My strategy is similar to the lasso idea shared above. I have them actually write 100, 1,000, or 10 (whatever they are rounding to) above the number. We turn the "1" into an arrow pointing down at the number we are trying to decide to leave alone or round up to next number. We circle any numbers below the zeros, and these are the numbers we look at to determine whether it's enough to push us UP to the next number or not. We discuss the "magic middle," 5, 50, 500 - and look at the circled number(s) to see if it is at, below, or past the magic middle. After a while, they get tired of actually writing the 10, 100, or 1,000 above the number, but I insist that they do it (lower achieving math group - need structure and routines), even on a test.
I have also seen a "mountain" strategy, w/ 0 at base of mountain, 1, 2, 3, 4 on left side (slopes back to zero - indicating no change in number to round); 5, 6, 7, 8, 9 on right side of mountain (indicating to round up to next higher number).

9. ### Newto3rdCompanion

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Oct 24, 2009

We underline the digit they're rounding to. They draw an "eye" (circle with eyelashes) around the deciding digit. Then we say 5,6,7,8,9 you go up, up, up TOWN (with a little attitude and mvmt!) or 4,3,2,1,0 you go down, down, down TOWN. They got it after practice. SO hard at first!! Some of my struggling math students want to go "down" to the # before (ex: 32 - round to 20 because we day "down"). So next year I'd like to come up with another rhyme to make it say "stay the same".

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Oct 24, 2009

Thank you! I will try some of these ideas on Monday and see if we can make some progress. They just don't understand why we're doing this yet. They're coming up with off-the-wall answers that have nothing to do with the question.

11. ### AliceaccMultitudinous

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Oct 24, 2009

You sound as though you and your kids all need a break.

I think I would drop it for now, and teach something with a reasonable expectation of success. Get them back into a groove where you teach, and they understand.

The year is still young. You can come back to rounding off in a few months when they've forgotten how confusing they found it in the fall, and when their math skills are stronger.

Sometimes kids get into an "I'll NEVER understand this!!!" mindset, and it's hard to break. So teaching something else, getting their confidence up, really can make a difference.

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Oct 24, 2009

I agree. I've been trying to keep pace with their homeroom as much as possible, but I might have to give up on that here.

13. ### bonnebFanatic

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Oct 24, 2009

Oh I am in a public library trying to control myself from cracking up! You describe third grade so well!!!!!!!!!!!!

However, I know it is not a laughing matter when you see all your hard work and progress go down the drain.

I soooooooo agree with Alice - drop it for now, move on to something with a higher success rate, let the kids start enjoying math again, and in January, use some of the strategies stated above.

When you are ready to pull out chunks of your own hair, it is time to take a break and do watercolors or something fun.

14. ### cutelilramRookie

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Oct 24, 2009

When I taught third grade I made a chart that showed the numbers 1-4 with a down arrow next to it and numbers 5-9 with an up arrow next to it.

I referred to the chart each time my kids needed help. They figured it out pretty quick.

15. ### lcluigs03Cohort

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Oct 25, 2009

here's the poem we use:

look next door
5 or greater
all numbers in front
stay the same
all numbers behind

it works pretty good. but i did have to teach some of my kiddos what 5 or more meant.

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Oct 25, 2009

Thanks everyone. These strategies are helpful because my second graders are working on estimating, one step of which is rounding a 2-digit number to the nearest 10. Thanks for sharing.

sarypotter, I want to also congratulate you on trying to keep up with the general ed classroom. You seem like you have high expectations for your special ed students - I like that. At our school, our special ed teachers seem to expect so little of their poor students. They seem to make little to no effort to try to mirror what the general ed kids are doing, so the special ed kids keep falling farther and farther behind as they years go on. Good job, sarypotter!

17. ### noreenkCohort

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Oct 25, 2009

To prove WHY estimation is important, just do a problem with actual numbers on one side and rounded numbers on the other. They'll see for themselves why estimating is so much faster. Then give them a restaurant menu and have them figure out what they can buy with a certain amount of money; if you give it a real world application then hopefully they can get over the "why do we need to know this?" stage quickly and move on to practicing the skill.

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