# Math Place Value Challenge

I mentioned on the math warm-ups post that we had been working on place value, and that mathematicians had a challenge to figure out how many sticks were in a big ‘ole pile.  They were given a small group (their partner plus another partnership) and two questions: How many sticks do you have? How can you count them in a way that will be easy to show someone else what you’re doing?

Each group was given a pile of popsicle sticks and they got busy!

As I went around to each group, I asked how they had decided what to do, and how they were determining how many sticks they had.  Most were bundling in 10s (yay!) and I nudged them to make an even easier way to see how much is in a big pile.  Could they continue to bundle and make a bigger group?

In the end, most groups ended up with bundles of 100, some 10s and–if their pile had any–some leftover 1s.  They put their collections back in the tubs, and marked how many they had with a post-it note.

Then we worked for a bit on how to model the numbers we had made.

The next step was to figure out how many we had altogether.  Many suggested that we could put our bundles together, but weren’t (at first) sure how to do that.  We talked about how they had made their 100s bundles–with 10 10s–and then guessed that we might be able to make some more 100s from the loose 10s in everyone’s tubs.

Left with a massive pile of 100s, that eventually led us to thinking there must be a better way to show how much that pile had in it.  I asked if they thought we could bundle any bigger numbers and honestly most of them thought I was crazy!  I just began collecting 100s in my arms and counting: 100, 200, 300, 400….and they got the idea.  They going until they got to…10 100s!  That was a great conversation next about what number we had just made.  10 100?  We figured out that it was a 1000, and that when we said “10 100” that helped us know about how many bundles were inside, but that it wasn’t the right way to say the number.  We stretched a big ‘ole rubber band and made a 1000 bundle!!  We counted the whole thing and agreed that we had one-thousand, four-hundred twenty-six sticks!

But how in the world do you WRITE the number one-thousand, four-hundred, twenty-six?  We gave it a go.  Many of us remembered that when we went from 2-digits to 3-digits it was a 100s number, and since we had 4 groups of sticks, maybe that meant our number had 4-digits…

Our model of this number–1,426–looked like this:

Many minds were blown as we figured out how many 100s and 10s were inside that big number.  We figured out that it was actually than just what the digit said, because of all of the groups inside of groups.  I loved how many kiddos kept saying, “Wow, this is fun!” and “Man, we’re learning so much today!”  Definitely lots of great mathematical thinking happening here!

UPDATE:  I got this email after the first posting of this story.  Love this stuff!  Thanks for sharing, Shannon. 🙂

Hi Jennifer!
You had so many math posts on the blog this weekend, that I wanted to share a story with you.  We have a Curious George story CD in the car that we listen to a LOT and in one of the stories George gets 10 dozen doughnuts.  The other day when this story was on, Millie asked me if 10 dozen was 120!  I was so surprised!  I said that it was and asked her how she knew that.  She told me “5 2’s are 10, and then another 5 2’s makes 20 and 10 10’s is 100 so, 120”.  It took me more than a minute to follow the math just because it wasn’t how I was used to thinking of problems, but she was totally right and I saw this “new” math stuff in action :).  It was kinda cool!  She was doing multiplication and didn’t even know it.  Thanks for teaching her such great foundational skills that allow her to do these kinds of problems in her head!

# Second Grade Math Warm-Ups: 8-24 to 9-4 (2 weeks worth!)

We’re in the swing of some things in 2nd grade.  Math warm-ups are one of those things–just I’m not yet in the swing of writing about them!  Here are last few warm-ups we’ve been working on:

Monday

Even though we worked on this last year, many kiddos had a hard time with the answer to this question.  We’ve since been doing many things (games, two-pen tests, conversations) to help us remember (or learn!) our doubles, near doubles and combos of 10.  They all form the basis for the bigger things we’ll do with numbers later on.

Tuesday

While I’m not entirely sure about the order of these next few warm-ups, the concept that is highlighted in them all is certain–the importance of place value.  Here was another that many had a hard time with.  Most of their answers were “I don’t know yet...”

Wednesday

Thursday

Tuesday, 9-1

This one was an easy connection to the essential question (EQ) I had asked earlier.  They had to think about place value to answer this one, knowing which numbers to add to each other.

Wednesday

Although not related to place value, this warm-up was related to a conversation we had had in math workshop the day before, and is definitely something all 2nd graders need to know how to do–tell time!  Often I will spiral older concepts into math warm-ups to keep them on the front of our minds!

Thursday

This warm-up, although badly worded, gave kiddos a little peek into a task I would have them do later that day in math workshop.  The question was really about the most efficient way to count a big ‘ole stack of something, which they’d have to do with a pile of popsicle sticks in a group that afternoon. I was happy to see how many of them were already thinking about bundling into 10s and 20s (rather than counting them all by 1s).

Friday

The warm-up on Friday was actually the end of the lesson from Thursday, and mathematicians completed their thinking with their learning partner in their math journal, which is different from how they MWU normally works.  I love how we can adapt this structure to work for our needs!  Since many of us have been doing this for a whole year now, it was easy to make that little tweak and still have them know what to do.  In this warm-up, kiddos were asked to model the counting we had done together the day before.