# Crayon Box Combinations

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## Objective

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

#### Big Idea

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!

## Setting Up the Learning

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?

## Opening Discussion

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?

## Student Work Time and Strategy Share

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.

## Independent Practice

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.

## Closing

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.