SWBAT find and model combinations of 9.
SWBAT represent combinations of 9 using equations.

Students think deeply about how to make 9 using different combinations of red and blue crayons. This builds number sense and sets them up for later math fact fluency!

5 minutes

**Review:**

We will start the learning today by looking back at the other combination lessons we have done, example-when we made all the different ways to make 8.

Partner Talk: What do you notice about the number sentences we wrote? (Allow this to be open, but highlight kids who focus on either the “flip-flop”, they all use + signs, they all equal the same thing, etc)

**Connect: **

Finding combinations of numbers will help us when we are learning to add and subtraction with these numbers.

**Objective: **Your thinking job today is-How can I find all the combinations of 9?

12 minutes

**Present the problem: I have 9 crayons in total. Some of my crayons are red and some of them are blue. Our job is to figure out all the ways we could make 9 using some red crayons and some blue crayons.**

**Focus: Great mathematicians can use strategies that helped them before when they encounter similar problems later. **This is aligned to MP.7 "Look for and make use of structure". This pushes students to think about how they can use what they already know about a certain problem type to help them solve a different but similar problem. This MP standard is also addressed when we talk about the commutative property, or the "flip flop".

**Partner Talk: Which strategy did you use to help you find the combinations of 8? **

Possible strategies (in rough order from least sophisticated to most) to talk about from the day before:

- Cubes-pull out some green and some orange, count how many orange and how many green
- Make a pattern with cubes-count how many orange and how many green
- Fingers-I have 5 on this hand and 3 on this hand, so 5 green and 3 orange
- Ten Frames-Same as above
- Counting on-choosing 1 amount and then counting on to the whole (I got out 6 green and I counted on 7, 8, so I needed 2 orange)
- Flip Flop-I got out 5 orange and 3 green so I switched it to do 3 orange and 5 green
- Organized List-1 orange, 7 green, 2 orange, 6, green, etc.

**Turn and talk: How can you use these strategies today as you are figuring out combinations of 9?**

15 minutes

At your desk, I want you to find one combination of 9. When you finish that combination, I want you to show how you did it in pictures, numbers and words.

**Student Work Time: **Students work for 5 minutes on their first combination. I'll circulate to see how students are solving.

**Student Share Time:**

Partner Talk: Show your partner what strategy you used and what combination you found. See if you used the same strategy or different strategies.

I'll choose 2-3 strategies to share out. As I share them, I will specifically highlight the commutative property (1.OA.B.3).* See attached anchor chart for example!*

**Guiding Questions:**

- How did he/she find this combination?
- How could we use this combination to help us find another one that is true?
- Have we found all of the combinations? How are you sure?
- How are these 2 strategies the same? Different?
- How are these combinations related (1 and 8/ 8 and 1)
**See attached video for some students partner talking about the "flip flop" or commutative property.**

I'll model writing "and" with a + over it to start to expose students more and more to the mathematical symbols. I’ll have all students write a number sentence to match their own combination.

13 minutes

**Group A: Intervention**

Students have the scaffold of a "crayon box" with 9 slots in it, one for each crayon.

**Group B: Right on Track**

Students choose a strategy to use to solve the problem. Their goal is to record combinations in number sentence form.

**Group C: Extension**

Students choose a strategy to find the combinations. They have different clues to figure out how many red and blue there are. The clue is, "I have 9 crayons. Some are red and some are blue. I have more red crayons than blue. What combinations could I have?"

*See attached documents for independent practice sheets.*

5 minutes

Students come back together for share out of ways to make 9. I'll chart the different combinations so that students notice the commutative property.