##
* *Reflection:
Missing Numbers - Section 4: Independent Practice

The most difficult part of this game is teaching kids to explain how they know the number should go there. However, the explanation is critical to meeting the Common Core mathematical practices standards. CCSS.MP3 says, "Construct viable arguments and critique the reasoning of others."

This lesson allows students to practice agreeing and disagreeing with each other in a developmentally appropriate way. The video attached to the Independent Practice shows a 15 second explanation by a student for why he knew 41 was missing. This is a great example for the depth that is needed as a beginning of the year first grader. He states the missing number, explains how he figured out the missing number, and also states what pattern he noticed on the hundreds chart.

Throughout the lesson, it is critical that students hear this type of explanation modeled by the teacher and by their peers.

*"How do you know?": Teaching Kids to Explain*

*"How do you know?": Teaching Kids to Explain*

# Missing Numbers

Lesson 5 of 13

## Objective: SWBAT identify patterns on a hundreds chart. SWBAT use patterns and structure of the hundreds chart to identify missing numbers.

#### Objective and Hook

*8 min*

**Review: **

You counted to 100 all the time in K. Let’s sing a song to help us remember how we counted to 100!

Get fit and count to 100 song by Harry Kindergarten. Sing it two times. The first time, we will sing it all the way through. The second time, I'll explain that great mathematicians don’t have to count starting at 1, they can start anywhere and keep counting on. Start the song again somewhere in the middle, and have kids count to 100 starting at that random number (somewhere around 50).

*See this link to the youtube version of Count to 100!*

* *

**Connect**

*We are going to be using big numbers in our story problems one day so we need to get really good at counting them in order. This will help us have a number line in our brains that we can use anywhere we go! *

**Objective** :

Your thinking job today is: How can I use what I know about a 100s chart to help me figure out missing numbers?

*expand content*

#### Opening Discussion

*12 min*

To set student engagement for the lesson, I'll start by saying, "Today I am going to try my best to trick you!! I am going to cover up a bunch of numbers and see if you can figure out what numbers are missing and then write those numbers in standard form. Before we do that though, I want us to look closely at the 100s chart."

**Guiding Question: What do you notice about how the chart is set up? What do you notice about how the numbers change/stay the same?**

I'll call on one student to share out to get the conversation started.

**Partner Talk: What other things do you notice about how the chart is set up?**

*Possible Responses to listen for:*

*The chart counts by 10s (10, 20, 30, etc).**All the numbers start with 1 on this row, then 2 on this row, etc**The numbers are getting bigger as I count.**All the numbers have 1, 2, 3,4, 5, 6, 7, 8, 9 in them.**If you go backwards, the numbers get smaller.*

* *

I'll call on a few students to share ideas about what they notice and chart these ideas.

After listing our ideas, we will chorally read the list they created.

**Connect to Mystery Number Game:**

- "We noticed so many new things about how the hundreds chart is set up! This is going to help us as we work on reading and writing the numbers to 100. Remember that our thinking job is:
**How can I use what I know about a hundreds chart to figure out missing numbers?"**

- I will hide 1 number (students close eyes).

**Guiding Question: What number is missing? How do you know?**

**Push kids to articulate a coherent reason for why they know that number goes there. Start with a number under 10 to help focus them on the type of reasoning they can use**

I will hide 3 or 4 more numbers and follow this same routine.

*expand content*

#### Game Rules and Practice

*10 min*

I'll present the game to students and we will practice a few rounds together. My goal here is for students to connect the class discussion we just had with the routine of the game.

**Missing Number Rules:**

- Partner 1 covers up 3 numbers with counters. Partner 2 can’t look!
- Partner 2 opens eyes and guesses a number. Partner 1 shows them the number and says, “How do you know?” or “No, the answer was ___”.
- Partner 2 guesses all the other numbers. Partner 1 has to ask “How do you know” or “No the answer was…”
- Record the numbers that were hiding in standard form.
- Switch! Keep playing until time is up!

I'll model a few rounds on the class hundreds chart, while also referencing the chart from earlier-“I see you know that all the numbers on this row start with a 2-we noticed that earlier on our chart”.

**Guiding Questions: These questions push students to explain their thinking more thoroughly, a key aspect of MP3, Construct viable arguments and critique the reasoning of others.**

- What did ___ do to figure out the missing number?
- Is there another way we could figure out what number is missing?
- How would we write that number?

*expand content*

#### Independent Practice

*15 min*

Students play the Missing Number game and record the numbers they find as they go on the recording sheet in the resource section. See attached video for an example of student identifying a missing number and explaining how he knew what number was there.

Students may need different levels of support in this game.

- Group A (in need of intervention): These students may play on the 50 chart to make sure they are solid on those numbers first.
- Group B (Right on track): Students will play as planned on the 100s chart.
- Group C (In need of extension): Students will play with the 120 chart and focus on how to write those numbers.

*expand content*

#### Closing

*5 min*

Today’s thinking job was: How can I use what I know about the hundreds chart to help me figure out missing numbers?

I will play one more round with students and close out the day.

*expand content*

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- UNIT 1: Creating a Culture of Math
- UNIT 2: Count to 100 Every Day!
- UNIT 3: 10: A First Grader's Best Friend
- UNIT 4: Charting and Analyzing Data
- UNIT 5: Inch by Inch, Paperclip by Paperclip
- UNIT 6: Properties of Addition and Subtraction
- UNIT 7: Shapes and Blocks
- UNIT 8: Understanding Equality
- UNIT 9: Adding and Subtracting: Base Ten
- UNIT 10: Solving 3 Addend Problems
- UNIT 11: Missing Parts: Unknowns in All Positions
- UNIT 12: Parts of a Whole
- UNIT 13: Tick Tock, Tick Tock
- UNIT 14: Time is Money: Hitting all the MD Standards
- UNIT 15: Base 10 Bonanza
- UNIT 16: What the WHAT?! Teaching Challenging Story Problems

- LESSON 1: Missing Numbers to 50
- LESSON 2: Counting Strips
- LESSON 3: One Less!
- LESSON 4: One More/One Less Hop
- LESSON 5: Missing Numbers
- LESSON 6: Number Puzzles
- LESSON 7: Counting Collections
- LESSON 8: Counting Collections: 100 Objects
- LESSON 9: Constructing Tens and Ones
- LESSON 10: Building Tens at the Lego Factory
- LESSON 11: It's Elementary My Dear Watson
- LESSON 12: Down on the Farm: Base 10 Problems
- LESSON 13: WANTED: Runaway Number