# Building Numbers 11-20

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## Objective

SWBAT build numbers 11-20 with tens and ones.

#### Big Idea

This is stage one for my class to begin developing place value. This lesson will use numbers in the teens to learn that numbers are made up of tens and ones.

## Rev Them Up

10 minutes

I love Schoolhouse Rock videos, and thank goodness for YouTube because we all have access to them. The use of catchy phrases and great music really catches first graders' attention. I previously taught a lesson on addition and introduced Zero the Hero in that lesson. (You can go here to catch that lesson and see how I introduced the concept of Zero the Hero.) Today, I will show the Zero the Hero video from Schoolhouse Rock to get my kids thinking about how a zero can add digits to a number and change that number based on where the zero falls in the place value of that number (i.e. 1 becomes 10 when 0 is added in the ones place).

There is a great book titled Zero the Hero by Joan Holub that is another great resource to share how zero affects other numbers. Conducting a read aloud with this book can add to the video experience and help your kids see what zero does. Check it out and enjoy!

## Whole Group Interaction

15 minutes

Need: 2 base-ten blocks, 20 ones blocks

Base-ten blocks are a great manipulative to use to model how numbers are built. It is very important for first graders to see place value at its most basic level because we are just starting to lay the foundation and we want their understanding of the basics to be strong. I want to present the rigorous Common Core standard 1.NBT.B.2b and show that numbers 11-20 are made up of a group of ten and some ones. The numbers 1-10 have provided them practice with counting objects and 1 to 1 correspondence, but now, starting with number 11, I can show them that ones can be added to a set of ten to create new numbers.

This activity will lay a strong foundation by also allowing my students to analyze each given number and make sense of the numbers by constructing models of place value using the base ten blocks (MP4) and their understanding of the base-ten structure of our number system (MP7). I want them to see the relationship between ones and tens by seeing that a group of ten ones can be traded for 1 tens block. I also want them to notice the numbers 11-20 all contain a set of ten plus ones that correspond to the number in the ones place.  As we build each number I will continuously point out the set of ten and then the different amounts of ones that are going with it to equal the number we are building. This is a concrete model they need to notice so that when we begin to build larger numbers above 20 they will begin to see the sets of ten in higher numbers.

Here is an introduction video of me building numbers 11-20 with my class.

Here is what I say: Students, help me count the ones blocks. (Count to 20 using the single ones blocks.)

Great, what do we have on our body that helps us count and how many? (fingers, 10)

A long time people only had their fingers to count with and when they wanted to go higher than ten they decided to create sets of ten. They would keep track of how many sets of ten they used to count whatever they were doing. This is one reason why our number system today is based all around groups of 10. Now we have tools to help us do the same thing and build numbers. This is a ones block. Count with me and show me how many are in this set. (Show them how 10 ones equals 1 ten)

Let's build the number 11; what blocks would I need? (a tens block and 1 single cube, 1 ten and 1 one)

Let's build the number 12 ...

As we build the different numbers, I will use a place value chart to show how many tens and ones we used to build each number. Everyone is helping me count and build each number, not just one selected student. We are doing each number as a whole class.

## Independent Practice

10 minutes

Need: Print the worksheet and copy for each student.

All of my students at this point will be using the base tens blocks to build their numbers at their desk, look at the models, and then draw. This will support my concrete thinkers to participate in the activity, though in future lessons many of my students will move away from using the concrete manipulatives.

I will pass out the blocks and have my students draw base-ten blocks and ones to build each number from 11-20. I will complete number 20 with them to make sure they see it is made of two sets of ten.

Also, I will relate the building of numbers back to a place value chart to help them see the connection of how many tens and ones creates the number.

They're working hard to get it all done.

## Closing

3 minutes

I will challenge my students and check for understanding with our closing today.

Students I am going to give you a piece of paper. I want you to partner with your neighbor and the two of you together show me how you would draw a base ten model for this number: 43

This number is greater than the numbers we mainly worked with today, but today's lesson taught my students about the base ten structure to our number system, and I am curious if they can apply this structure to representing a new, challenging number (MP7). They will have the support of their partner, and it will give me insight as to what we need to continue working on.