composing & decomposing {CC K.NBT.1}

Composing & decomposing numbers.  This is a term I had to keep going back to because as I was looking for new strategies and ways to teach it I was like..."Wait.  What does that even mean?!"  :)  Basically, composing and decomposing is an intro to place value and helping students see that a "10" is really made up of a group of ones.

Here are a few things that have worked for us.  Starting with...s-l-o-w it down.  This is a concept that takes their brains in a new direction of thinking so let your math centers hibernate for a week or so and focus on some good, whole group instruction and practice time.

{Sing it}

Harry Kindergarten has done it again.  He's revamped his Numbers in the Teens song to get the kids singing about groups of tens and extra ones.  I started introducing this during our math brain break time a couple of weeks in advance just to get them familiar with it.

Then we moved into "acting it out" while we sang along.  Each kid built a 10 tower using pop cubes of the same color.  All of the other pop cubes were spread out in the middle of the carpet.  As we sang along, I paused the video at each number so the kids could grab another "one" and double check their groups.  I told them the color of their ones didn't matter because I wanted the difference between the group of 10 and the single ones to be clear.

We repeated this to start the lesson for the next few days and as they got more familiar with adding a one, I didn't have to pause the song anymore.

{build it}

Next, I grabbed a dry erase board and wrote a random number from 11-19 to see if they could still build it when the numbers didn't go in order.  We practiced this for a few days as part of the lesson.  Then, to flip flop their thinking, I built a number using pop cubes and let the kids all have dry erase boards.  This was a little harder because some of them wanted to count all of my cubes instead of seeing the 10 tower as a known group.  {This was also a great teaching moment to explain WHY it matters how they write the numbers - if they wrote 15 as 51, I'd build 51 to show the difference.}

Again...practice for a few days.  :)

Once I was ready to introduce practice centers, this was an easy activity I knew they could do on their own.  The kids took turns writing a teen number while their friends built it.  {you can see our pre-built single colored 10 towers & multi-colored ones in this picture.}  They passed the dry erase board around so they could each practice being the teacher.

{draw it}

This could be done in a center but I used it as my last whole-group activity to get a better grasp of who was understanding the concept.  We did 11 and 12 together as I modeled how to draw on the board.  Then they finished the rest on their own.  {This folding didn't allow us to draw 19 but I figure if they could do 13-18, that was a pretty accurate measure.}  ;)

{add it}
We learned this game in partners and then they practiced on their own when it was time to rotate centers.  The first 10s frame is already built to keep that group intact.  My kids drew a number card, added that many counters to the second 10s frame and wrote the number sentence.  I also had them explain their board to their partner before erasing - "14 is a group of 10 plus 4 ones."

{practice it}
This week, in addition to our current review centers, I'm going to introduce this {free} matching activity from Clearly Kindergarten...

...as well as some of the fabulous games and practice centers from my friend Leslie at KindergartenWorks!

Hang in there.  They will get it!!  :)  And remember to enter for your chance to win an Origami Owl locket:

{winner chosen on Sunday at 5pm Eastern time}