SWBAT solve for the missing whole in a subtraction problem.

Who doesn't love Laura Numeroff''s If You Give a Mouse a Cookie?! Connect to that well loved story and play a cookie themed game to practice start unknown subtraction problems.

10 minutes

**Read Aloud:**

We will read If You Give a Mouse a Cookie by Laura Numeroff. This book is a classic first grade favorite, so expect a lot of giggling! If you don't have the book, you can grab it on Amazon or watch this digital version on youtube.

**Hook and Objective:**

The mouse in this book LOVES cookies and he is going crazy for cookies! We are going to play a game today where one person is the Cookie Holder and one person is the Mouse, the Cookie Stealer!

**Your thinking job is: What strategy can I use to help me figure out the whole in this subtraction sentence?**

15 minutes

In this game, I am going to pull a card and start with that many "cookies" (cubes/counters) in my cup. I am not going to tell anyone how many "cookies" are in there. Then my partner is going to steal some!! Then I’ll show them how many are left. The partner has to figure out how many we had in the jar at first.

**Game Rules:**

- Cookie Holder: Draw a card. Put that many cubes in the jar. Keep it secret!
- Stealer: Roll a dice and steals that many.
- Cookie Holder: Show them how many are left.
- Stealer: Figures out how many they started with.
- Cookie Holder: How do you know?
- Record. Switch!

I’ll model using the Cookie Game Recording Sheet and Cards.docx with another student. See attached recording sheet for what my chart will look like!

**Step #5: How do you know? **MP3, construct viable arguments and critique the reasoning of others, asks students to constantly be able to supply reasoning for their thinking. I always make sure "How do you know?" is a step in our games. All students need constant practice explaining their thinking.

- When we get to Step #5, I’ll say, “Pretend you are all the stealers! Turn to a partner and ask: How do you know how many I had in the jar at first?”

**Strategy Share:**

I’ll have 2-3 students share their strategies quickly. This gives them practice explaining how they solve a problem, and presenting to a group! One of the CCSS shifts was towards standards on speaking and listening skills-students should practice these skills throughout the day, including math!

**Watch one student present here!** She explains how she solved and presents to the whole class as a "student leader".

- Big points to drive home:
**Why**kids knew the number had to be bigger**How**to write the addition sentence that matches the think addition strategy**Why**the student combined the two numbers

I’ll chart these strategies so students can use them later to help their own thinking! Strategy charts provide a mental road map for students who are trying a new strategy.

10 minutes

We will practice a few rounds together as a class. First, I choose a partner to play with me in front of everyone. Then I choose 2 partners to play together and the class watches. This ensures that students know exactly what to do to play the game, and thus learn the concept!

**Watch a video of 2 students practicing the game!** You'll see how they model for the class, as well as how I remind everyone of the rules as we go.

I'll have an enlarged version of the recording sheet on chart paper so I can model how to record each round. See Class Recording Sheet for an example!

I'll also make sure to model what to do if the “stealer” gets the whole wrong. This is important so students get practice at the other half of MP3, "Critique the reasoning of others". Without explicit instruction on how to do this, students may just breeze by a mistake and not stop and correct their partner!

- I model it like this. After someone gets the answer wrong, I say, "That isn't how many I had at first. Try again". If they still get it wrong, I say, "Watch me. Now you try it".

15 minutes

Students play the game with a partner. I try to plan out my math partners before the lesson. You want the game to be fun and educational for both partners, so they need to be very similar in what strategies they are using right now. Pairing a student who needs cubes with a student who can do everything mentally leads to frustration for both partners.

**Group A: Intervention -**Students should do numbers under 10. Keep the number super small. This might be best to play in a small group with the teacher.**Group B: Right on Track -**Students play the game with numbers under 15**Group C: Extension -**Students play the game with numbers under 30

Cookie Game Recording Sheet and Cards.docx are attached!

See attached Start Unknown Strategy Guide.docx for possible strategies students might use to figure out the missing whole. It includes questions to ask to push them to more efficient strategies!

5 minutes

We will end the lesson by quickly sharing a few of the strategies I saw students use during the game. I will particularly focus on a counting strategy because by this point I want students using more efficient counting strategies to solve. (For example: To solve ____-3=7, students might say, 7, 8, 9, 10).