SWBAT add with more than one addend. SWBAT use combinations of ten. SWBAT add combinations of ten up to twenty.

A twist on the word game scrabble. Using playing cards, students will make strings of numbers that equal 20.

10 minutes

Advanced Preparation: Create a Venn Diagram that asks the following questions; Do you like chocolate creemes, vanilla creemes, or chocolate and vanilla twist creemes?

*Note: Creemes are what northerners call soft serve ice-cream.

"I am going to ask each of you to tell me what kind of creeme you like to eat. As you give me your answer, I will record it on this graph. We have talked about this type of graph before. Can anyone tell me what it is called? Yes, it is a Venn Diagram. If you answer vanilla, where would your answer go? If you answered chocolate, where would it go? What if your answer was chocolate and vanilla?"

I then call on each kid to answer the question and record their answer in the appropriate spot on the graph. There is a photo, in the section resource, of the completed graph.

Once everyone's answer has been recorded, I will then ask them to make some statements about the results and to express an equation that represents the data.

The students are meeting the 1st grade expectation of organizing, representing, and interpreting data with up to three categories (CCSS.MATH.CONTENT.1.MD.C.4).

15 minutes

Advanced: You will need a set of playing cards for each team of three. You should have them take out the face cards and use the A's as 1's. I used ten frame cards (you can see them in the video).

I have the students sit in a circle on the carpet. I then introduce the game called Twenty-Twenty.

**Note: This game was created by Adrienne Magida, a colleague of mine. She is happy to share this game with anyone.

*"Today we are going to learn a new game called Twenty-Twenty. You will play in groups of three (this game can be played with 2-6 players)."*

I start by dealing 5 cards to each player. Each player must also take 6 of the same colored chips (i.e. one player can have 6 blue, 1 player can have 6 read, and one player can have 6 yellow). I will then place one card on the table as the starting card.

*"You will take turns placing cards either horizontally or vertically to create a string of addends to twenty (like scrabble). Once you place a card, you will then take a new card from the deck so that you have 5 cards in your hand again. *

*If you place a card and create a string of twenty, you close off that string by placing two of your chips at either end of the string. That string is now closed and players must play off other horizontal or vertical strings.*

*The first player to place all of their chips wins the game."*

CCSS expects that first graders are adding within 20 and demonstrating fluency for addition within 10. For this game, they are engaging with this standard by using strategies such as counting on, making ten, and creating equivalent but easier or known sums within 20 (CCSS.MATH.CONTENT.1.OA.C.6).

15 minutes

I ask the students to come over and face the large easel in my classroom. I want to have a discussion about additive reasoning. I quickly list al of the facts of ten, in a vertical list, on one side of the easel. I then use the other side of the easel and write 11+__=20.

**"We know that 11 is one group of 10 and 1 one. So, we know we have ten and need to make a second group of ten to equal 20. If we have 1 one, what would go with it to make ten? Yes, 9 because 1+9=10. So 11+9=20."**

I draw this out on the easel so that students can get the visual image of what is going on. I then repeat this with the rest of the facts to 20.

*"When you are looking for combinations for 20, I want you to use your knowledge of 10. I want you to think of your ten facts."*

In this case students are meeting CCSS.MATH.PRACTICE.MP8 because they are noticing a repetition in calculations, using shortcuts to solve for 20, and are applying general methods in using ten to solve for twenty.

5 minutes

The students will complete a Mad Minute sheet during this part of the lesson. Click here to read about the activity and to see the resource. Once you click the lesson, you will have to go to the continued practice section of the lesson.

5 minutes

I end today's lesson by asking each student to complete the 11 Apples and Bananas problem (section resource). We have been working on these type problems throughout this unit and I want to see if students are starting to apply strategies to find all of the combinations.

I have included two example of student work. Student A's work models a student starting with the highest of one type of fruit and adding the minimum of the other type and then working her way, by subtracting one and adding one.

Student B's work models a student using "flip facts." Unfortunately, she ran out of time and didn't list all of the combinations, but I know (from previous work) that she does know them.