Friday, March 23, 2012

Getting Interactive with the Common Core: Decomposing Numbers

I am always looking for fun, simple, interactive ways to do math with my kinders. I especially like activities that they can become independent at, but produce something so parents can see what we've been working and I can evaluate student progress. And, like my students, I am very tired of pages that require them to show what they know by coloring. COLORING IS BORING! Five year olds like to DO things, and by golly I am going to give them what they want!

So my students learned how to decompose numbers in a hands-on experience with unifix cubes, and then continued to develop the concept using 1" squares of construction paper in a representation of the cubes. They glued the squares into decomposition patterns and recorded the corresponding addition sentences.
Hands-on activities for decomposing numbers in kindergarten

Four Different Sets of Decomposing Number activity pages are available for purchase in my stores Teachers Pay Teachers and Teachers Notebook.
Hands-on activities for decomposing numbers in kindergarten

Shop Decomposing Numbers on Teachers Pay Teachers
Shop Decomposing Numbers on Teachers Notebook

(And just in case you're wondering - YES! I do use the word decompose when I tell my kiddos what we're doing. I like for them to hear the grown up word for what they're doing. So I sprinkle in the big vocabulary for the kids who love new words and also mix in some other expressions like, How else can you make 5? or What's another way to build the number 8?)

But I digress. Back to this week's math activities. I introduced the concept of breaking numbers into 2 parts using 2 colors (green and orange) of unifix cubes. I had cubes, and so did each students. Everyone also had a whiteboard and dry-erase marker. We started VERY simple.

Day 1: Introduce decomposition with Unifix cubes

Below is a summary of my dialogue with the students:
Ok everyone, I want you to hold up  5 green cubes that are all connected in a stick. Show me a stick of 5 green cubes.  

Great! Look at your cubes. How many green ones do you have? (5)  How many orange cubes are in your stick? (0) 

I could write an adding sentence about my cubes! What would the adding sentence be for the green and orange cubes in my stick? (The answer is 5+0=5, which I recorded on my whiteboard after a student provided the equation.)  

Super! Now let's trade one of our green cubes for an orange cube. Hold up a stick that still has 5 cubes, but now one of them is orange. Look at your cubes again. Now what would my adding sentence be? (4+1=0, which I also recorded)

We went through this entire process, continuing to swap one cube at a time until we reached 0 greens plus 5 orange. At which point, I asked the class to look at all of the sentences they told me and look for patterns. (Some numbers go up, some numbers go down, and the sum stays the same). We took a few minutes to discuss WHY those patterns happened.

Hands-on activities for decomposing numbers

Then we repeated the process using another set of cubes (3 greens, 0 orange). This time we traded cubes together and all of the students recorded the addition sentences on their personal boards too.

Day 2: Review Decomposition and Introduce Paper Activity

The following day we began with a quick review using 2 colors of cubes (blue and red) and our dry-erase materials. This time we decomposed the number 4. After recording the addition sentences, we took a few minutes to discuss patterns we observed. Now they were ready. I introduced their first decomposing activity page. We did Four Ways to Decompose 3 because it was a short activity and VERY familiar from the day before. The kids LOVED it!

Day 3 and Beyond: Move Toward Independent Practice

We continued to discuss decomposition, but our discussion became quicker each day and the class was more eager to complete the activity with paper tiles. Next week I set the Decompose 2 worksheet in my lesson plans as a bellwork activity. I am completely confident in their ability to handle the activity independently.
Hands-on activities for decomposing numbers in kindergarten

We also use subtraction to decompose numbers in my classroom. Click here to read all about the experience. 

Have a great day!


  1. I agree...I get tired of all the activities that require them to only color. I don't mind if it's in combination with something else, but too often that's not the case. I love this post! Thanks for sharing!

  2. This is great! I like how you start at the concrete level and move forward. It really increases understanding! I am your newest follower. I work with first grade- but feel free to visit sometime:

    Candi : )

  3. I love this idea--thanks for sharing! I am thinking I might do it with a paint dobber!

    meet me at the zoo...

    1. Me too - wonder if we could do it with the little stickers that you use often as well??

  4. Thank you for sharing! This really helped me out this week and my kiddos seemed to get it! Thank you so much!!

  5. Great idea! Thanks for sharing!

  6. I used your freebie today! The kids loved it, thanks!

    1. You're welcome - I'm glad it was helpful to you!

  7. Great idea! Thanks!

  8. thanks for sharing your idea. love it!

  9. If everything was this easy, life would be a breeze!! Love the paint dabber idea, too!!!! Thanks for sharing!!!

  10. I just recently found your blog and I LOVE all the detail you put into your posts! I also teach kindergarten and math is the one area that my kiddos love but struggle with at the same time. It is hard to keep them engaged the entire time because they know recess is next, so I am always looking for fun and creative ways to teach math! Thank you for sharing! :)



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