Lesson 2: Learning Another Addition Strategy

​Today you will…

Use the strategies you learned last week to figure out the number of animals in the desert scene of 1001 Animals to Spot.

• You will also learn a strategy for adding 9 to numbers.

Let's figure out how many animals are on each of these pages.

• Let's start with the left hand page

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Open your book to pages 6-7.

Did you know?

One way to add 9 to a number is to add 10 and the subtract 1.

Adding 9 to a number

Here's how I think about adding 8 + 9:

• 8 + 10 = 18

• 1 less is 17( 18- 1 = 17)

Here is how I think about adding 22 + 9 :

• 22 + 10 = 32

• 1 less is 31( 32 - 1= 31)

We will read the names and numbers of the animals.

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​Let's look at page 7.

​More than one way!

I will show you one way we can add the numbers from page 7.

• I will keep track of my thinking by crossing out numbers as I use them and writing equations.

• To start I know that 6 + 8 = 14

6 10 8 9 10

​What's next?

Next, I'll add 10. How much is 14 plus 10?

6 10 8 9 10

Now I'll add the other 10. How much is 24 plus 10?

24 + 10 =

Only 9 left!

I can use the strategy for adding 9.

• I will add 10 to 34, getting 44.

  • Then take away 1.

  • How much is 34 + 10 = _____

  • How much is this number minus 1? ______

10 10

4 10

8 4

10 8

9 9

Let's Try

It helps sometimes to change the order of the numbers to make branching easier.

• I'll write the 10s together.

We will work as partners on WorkSpace page 3.

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What's Next???