## Tuesday, September 18, 2012

### Comparing Numbers

The CCSS for Mathematics requires 2nd grade students to compare 3-digit numbers.  Pay close attention to the wording:
2.NBT.4--Compare two three-digit numbers based on meanings of the hundreds, tens, and ones digits, using >, =, and < symbols to record the results of comparisons.
Notice how the comparisons are based on a understanding of place value.

Keep in mind what a foundational year 2nd grade is for place value.  The ones, tens, hundreds structure and the relationship between digits in each place sets the stage for all work that students will do with larger numbers and decimals.  No pressure. :)

So how do we build that deep understanding?  First and foremost--LOTS of concrete learning.  Move from showing tens and ones using groupable objects (like linking cubes) to building numbers with base-10 blocks.  And then never put the base-10 blocks away!  All...year...long.

After students have had plenty of concrete practice, introduce a way for them to represent (draw a picture of) their numbers.  The anchor chart below shows an easy way to represent hundreds, tens, and ones.

When students move from building numbers to comparing numbers, go back to the base-10 blocks.  Have students play games where they build, represent, and compare numbers.  Here's a place value mat partners can use to build and compare numbers.  Note that it prints on 11 x 17 paper.  You can scale it down to print on smaller paper, but then the base-10 blocks won't fit.  Click here to grab yours.

Finally, with a strong foundation in place, they can move on to ordering numbers.  Again, notice the base-10 block representation.

1. Love, love, love your blog and this post, but I have an issue with the last picture. We use the vocabulary Least to greatest. Biggest and smallest may be the way they think of it, but we need to start moving them towards academic vocabulary.

Just my two cents.

1. Yes, absolutely! This was the first day ordering was introduced, so I imagine this teacher was probably using familiar words as a way to introduce the more formal vocabulary. In fact, I'd be surprised if there wasn't an anchor chart showing different ways to say 'least' to 'greatest' in the near future! :)

2. I so enjoy reading your blog!!! Thanks for the visuals and printables as well.

1. It's my pleasure! I'm glad you find my blog useful. :)

3. Here's a quick video on place value from you tube. It is something that I had my students listen to after coming in from recess or while cleaning up. It is a fun compliment to place value instruction and a good review.