Work on decomposing numbers 11-19 by breaking numbers into groups of tens and ones.

Here is a free Valentine-themed printable workmat and matching number cards that you can use with your kindergarten class.

Let me show you how to use it, make it and give you some ideas on how to get the most from it.

## How to use it

First, let's understand what decomposing numbers means.

In kindergarten, decomposing numbers means to break the number down into parts. And, most often, in kindergarten it means breaking down a number into it's groups of tens and ones.

**Continue reading >>** What is decomposing in kindergarten and why is it important

Now that we know what it means, we want to give our students lots of varied ways to practice breaking numbers apart - especially the teen numbers.

**The more hands-on, the better.**

I love using ten frames the most to practice both composing and decomposing numbers, but for this activity, we're going to use base ten blocks.

Here's what students do:

1. Students will pull a number card and break it apart. They will figure out which numeral represents the number of groups of ten and which represents the ones.

2. They then show that using a group of ten (a base ten stick) and write the matching numeral (a one) on the mailbox to represent one group of ten.

3. They repeat the same thing using individual ones (base ten single blocks) and write the matching numeral on the envelope to represent how many ones there are in the number.

To check their work, they can count all of the blocks together starting at one, or they can start counting at ten (and touch the entire base ten stick) then keep counting on.

4. They clear their workmat of blocks, erase their written numbers and keep their stamp as a "point" to keep track of their work.

5. They repeat the activity and pick a new number stamp card to know what number to decompose next.

## How to differentiate it

As it's created, this activity just focuses on numbers 11-19, which is the number range for this kindergarten standard.

You can however easily tweak a few things to make it more of challenge or give your struggling students more support.

### To make it harder

To make this activity more challenging, use the blank number cards and add in numbers 0-10 and 20.

This is a really great way to see if students understand the lack of a group of ten in numbers 0-10 and the need for two groups of ten in 20.

If they can do this, then they are ready for more.

To make it an accelerated activity, use the blank number cards to make any assortment of numbers to 99. It's great for students who already can count and recognize numbers to 100 and can accurately decompose numbers to 20.

If you make either of those additional card sets, be sure to print off sets in different colors so it makes it easy for students to know which cards to use and clean up.

### To give it more support

To give more support to this activity be sure to **include a number chart** to 20 so that students can count on the chart and find the matching number stamp and identify the number correctly.

You can also **draw labels under the numbers** that show tens and ones to help them recognize where to break the numbers apart. I use tens and ones labels with words and pictures. We use these labels all the time - especially during calendar binder math time - so students become very familiar with their meaning.

Another alternative to giving it support is to **draw the solution on the back** of the stamp so students can flip it over to check their own work.

## How to make it

Now that you know how to use it and how to differentiate it for your students - let's make it.

First, download these free mail-a-teen-number sheets. [terms of use] [downloading help]

Then print your workmats either in color, black and white or on construction paper. Slip those workmats into a plastic protector sleeve or laminate them.

Print the number stamp cards 11-19 onto construction paper (or make the modifications we covered earlier) and either laminate or leave them as is. I find that construction paper often holds up well enough, I don't need to laminate.

If you're going to use differentiated sets, then consider putting the stamp card sets each into their own Ziploc baggies and labeling them so your students know which ones to use.

Place the workmat and cards together along with a dry erase marker, eraser (a tissue or baby socks from the Dollar Tree work awesomely), and some base ten blocks.

You're ready to use this with your class!

## Let's wrap it up

There you have it - a free activity to work on decomposing teen numbers in kindergarten with a fun, Valentine's Day theme.

I hope this mail-a-number activity can come in handy as you work to give your students varied practice with composing and decomposing numbers.

Want more ways to help them practice? Try one of these:

- How to Teach Decomposing and Composing Numbers
- Composing and Decomposing Numbers (11-19) Differentiated Materials
- Composing & Decomposing 11-19 Cards for Magnetic Drawing Boards
- I Spy Decomposing Numbers with Equations

Want more free Valentine things to do with your class? You might just love these 21 Valentines Day Freebies for Kindergarten.

If you like what I do here on KindergartenWorks, then be sure to subscribe today. I look forward to sharing ideas with you weekly.

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