Rounding to the Closest Ten Above One Thousand

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Objective

SWBAT apply the principles of rounding to the closest tens to numbers greater than one thousand.

Big Idea

The principles behind rounding to the closest ten and hundred are EXACTLY the same whether the number is "small" (867) or "large" (123,867).

Opener

10 minutes

Guided Practice

15 minutes

The goal of this guided practice is to provide students with clear example of the inherent consistency of rounding any number to the closest ten.  There is value in exposing them to the idea that the procedure for rounding to the closest ten remains consistent regardless of the number of digits in the number.  Though this task still feels much more difficult to many of them, even if they aren't able to do it successfully independently, they will still take away a reinforced sense that the important digits to look at when rounding to the closest ten are the ones and tens place.  Therefore, irrespective of their diverse levels of independent proficiency with this skill, I work through these examples with the entire class.

Independent Practice

30 minutes

Enrichment is rarely a case of more or faster, but in this particular scenario, I do give the students who are ready for enrichment the page with the largest numbers.  For the students who need extra support or simply more practice before moving on, I give them a chance to practice rounding to the closest ten with numbers less than one thousand.  For students who are on level, I provide them with the opportunity to work with numbers in the hundreds, thousands and ten thousands.

I have provided study pages here but in my classroom I wrote the numbers on the board in 3 different columns.  When they work in their notebooks or on scrap paper it doesn't look as neat as a study page but the learning is the same.  I also did this for practical reasons (no printer, no paper, no copier) but when I teach this again I will do what I can to go back to the study page because the extra effort for them to draw out the number line each time detracted from their ability to concentrate on the math!  Some of them wanted their lines to be perfectly straight and no matter what I said, the minute I turned my back, they had their rulers out to draw perfect lines again!

Finally, and this is worth nothing, I let my students self-select their level, with a few exceptions.  I think that's an important part of developing metacognition - they need to learn to recognize on their own when they need additional support or practice and when they are ready to move on.  In this instance, I had two children for whom I made the choice, on child who is very advanced and always chooses the shortest, easiest path possible and another child who sometimes struggles yet thinks they are correct, always, and persist at tasks far out of level without the prerequisite mastery of the basics.

Wrap-up

8 minutes

At the end of this lesson I ask a tricky question,

"When would you ever need to round a very large number to the closest ten?"

I first have them present examples of when they might round to the closest ten with numbers in the tens or hundreds (pencils to class, stickers, cookies to pass out, cost of an item in the store) and then we work together to try and think of a time when we'd round to the closest ten (high level of exactitude) with a large number, for example, 117,234.  

If your class comes up with any ideas about this please share them with me!