Pick a Card, Any Card!

Present problem: ____ - 6 = 4

In today's game, we will have to think about which number card could go in this blank to make the number sentence true. I am going to pull a few cards. We will discuss and prove whether or not that number makes the equation true.

First Card: 2

I chose this number to go first because it is the most common mistake students make with start unknown problems. Students recognize a well known fact family, but don't closely attend to the equation. In this case, students might see the 6 and 4, and know that 2 is in that family. Starting here addresses this misconception head on, setting students up to be successful in future problems.

Guiding Questions:

• Partner talk: Does this number sentence make the equation true? Why or why not? Listen to this Partner Talk discussion-you'll hear one student explain clearly about how he knows for sure.
• I'll choose 1 person to share why this number does not go in the blank. We will chart the response on chart paper. 

Second Card: 6

Guiding Questions: 

• Does this number sentence make the equation true? Why or why not?
• I'll choose 1 person to share why this number does not go in the blank. We will chart the response on chart paper.

Partner talk: I keep getting the wrong answer! Show me on your white boards what number needs to go in this blank to make the equation true. Watch this Whiteboard Whip Around-you'll see multiple kids' strategies on their whiteboards.

After student discussion, we will chart how to figure it out on chart paper.

See attached Class Chart!

I decided to have one student model using cubes for the class. Concrete models are very important for first graders; students learn starting with the concrete before being able to understand picture and abstract representations. Watch this Concrete Model video for our discussion!

Present Problem: 12 = 9 + ____

Guiding Questions:

• Where is the equals sign? Where is the plus sign?
• Does this equation say 12 + 9?

I'll have students prove or disprove each card on a whiteboard.

First Card: 21

• Does 21 go in the box? Why or why not? Prove your thinking on your whiteboard.
• See how one child proved that this answer was wrong in this Prove it! picture. She not only explained what the answer should be, but figured out why someone might think the answer is 21. This is aligned to the CCSS MP3, Construct viable arguments and critique the reasoning of others. She could explain why someone else might make a mistake and prove that it is wrong!

Second Card: 12

• Does 12 go in the box? Why or why not? Prove your thinking on your whiteboard.

Third Card: 3

• Does 2 go in the box? Why or why not? Prove your thinking on your whiteboard.

After each card, students will share with a partner whether or not that number completes the equation.

I'll model the game on the rug a few times for students. I'll also post the rules so they are easy to reference throughout the game.

Rules:

1. Each partner group gets a gameboard and a set of number cards.

2. Partner 1 pulls a number card.

3. Partner 1 checks each number sentence. Does this number make any of the statements true? If so, the partner places the number there.

4. Partner 2 pulls a number card and does the same thing with that side of the board.

Keep playing until all of the spaces on the board are full.

After modeling the game, I'll have students play in partners for 15 minutes. 

Differentiation:

• Group A Game Board: This board can be found for free here from K-5 Math Teaching Resources! Numbers to 12, multiple game boards included.
• Group B Game Board: Same game, but with numbers to 20 (includes start unknown subtraction. Watch this Game Play video to see one partner group in Group B playing! 
• Group C Game Board: Same game, with numbers to 50 (includes start unknown subtraction)

Pick a Card Gameboards.docx attached!