Math Tip Monday September Number Sense Grade 3


Math Tip Monday September:  Number Sense
Rounding.  What teacher doesn't dread having to teach rounding.  As a third grade teacher, I have been accustomed to receiving 2nd graders who had exposure in learning how to round.  But that was with the old California Math Standards.  Now that California has adopted the Common Core Math Standards, rounding is a whole new concept to these new third graders!  Now it is true that 2nd grade does focus on place value to 1000 and teaches the students to mentally add and subtract 10 or 100.  Those are necessary skills to rounding in third grade.  Click READ MORE below to see the entire post.


Rounding Without Rhymes
Rounding Without Rhymes

So, how did I teach rounding this year?  In the past I have used number lines and chants and rhymes.  But I decided I needed something new and different to teach it since it seemed that students would eventually forget to round in the later part of the year.  So I looked around on Teachers Pay Teachers and found this amazing resource by The Math Spot (read the blog post that explains it in detail!) called Rounding Without Rhymes.  I used it for 2 days to teach rounding to 10s and 100s (I would have wanted to use an extra day but you know how it is with a district pacing guide!).  It worked great!  In a nutshell, the resource helps students to see the scale of numbers, especially the all important middle or halfway number.  I can say that by using this resource, about 80% of my class has a good grasp of rounding and about 50% can now do it in their heads (while the others rely on number lines).  It's a great resource and I would certainly check it out.  I am definitely going to use it next year again!

Rounding on a number line
Rounding on the number line using a white board.

Once the students understood the concept of rounding, we practiced on white boards.  I would give them a number.  Then they had to draw a number line with the preceding 10 and the next 10.  Then they had to locate the middle number and place it.  Then they place with an X the number they have to round on the number line.  From there they determined which 10 it was closest to and circled it.  We did the same procedure when rounding to the 100s.  This task was more difficult because for many students that middle number was hard to get!  With guidance, they eventually got the hang of it.

From that point, the students actually had to use rounding to get an estimate when adding multi digit numbers.  This is not a skill that is used only once and forgotten!  They will have to round in subtraction, multiplication and division.  So to keep up the skill I am having them round a few times during math or during the day as sponge activities that take no longer than 5 minutes:

  • stand up sit down:  I say a number, then I say:  stand up if you think the number rounds to __ or  sit down if you think the number rounds to ___.  This also gives me a quick visual check to see who's still not getting it.
  • find your rounding partner:  half the class gets a card that either has 10, 20, 30, 40, 50, 60, 70, 80 or 90. You can also do this with hundreds as well.  Then the other half gets a card with a number between 0 - 100.  When I give the signal, the class has to find a partner whose number will round to that 10. 
  • random call:  Literally throughout the day I will just randomly say a number and the first person to round the number to the nearest 10 or 100 gets a class reward ticket.  Hokey but it works!  
Rounding Cards
Rounding Card FREEBIE



Rounding Cards
Rounding cards with 10s and 100s

To get you started with your students on rounding on a number line, I've included a FREEBIE!  Rounding Cards.  Print them, laminate them, then cut them.  Use them on a document camera to demonstrate to your students the procedure for rounding on a number line.  Included are cards for rounding to the nearest 10s, 100s and blank cards to make your own!  Enjoy.  Don't forget to let us know how you teach rounding by using the comments section.  Also, don't forget to continue with the Math Tip Monday links.  Happy rounding!

Update:  Apologies to those who tried to download the FREEBIE.  I had the incorrect link, but it has now been fixed!




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