# Combine and Compare

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## Objective

SWBAT find the sum of two or more quantities by counting all, on, or using number combinations, compare the sum to another sum, and visualize and retell the action in an addition situation.

#### Big Idea

Blending is not just for ELA teachers! Today students will learn to "blend" (combine) two sets of dots and then compare the number to another using greater than by playing versions of previous learned activities.

## Warm Up

5 minutes

Like yesterday, I am going to have the students count back to 1.  I remind the students that means the number that we draw (from the deck of 1-30 cards already created in previous lesson) will be the number we start with.  Using the number line, mark the two numbers and then rote count as a class. This counting can be related to addition or subtraction by adding one each time or subtracting one each time (CCSS.Math.Content.1.OA.C.5).  I use a pointer to emphasize the one number for one touch on the line as we count back.  I will continue to play this game as time allows.

## Introducing Combine and Compare Me

15 minutes

Advance Preparation:  You will need to have decks of the Me cards and Number Cards for this activity. To make the Number Cards, you will need to make 4 copies per deck.  I use 10 frame cards that are supplied by another company.

I start by explaining to the kids that we are going to learn a new game called Combine and Compare Me with Dots.  It is played the same way as me, except that you are combining two cards and finding the total number of dots.  Once you have the total, you compare it to your partners total and then say "Me" if you have the greater amount of dots.  The students are making making viable arguments by explaining how they know that they have more dots (CCSS.Math.Practice.MP7).  If the totals are the same, the players each turn over one more card to determine the winner of the round.  Keep playing until all of the cards have been flipped.

Then I show the students the number cards and explain that they are going to play the same game but they will use number cards instead of dot cards.  This game is called Combine and Compare Me with Number Cards.

Since the children have played similar versions of this game previously, the introduction should go rather quickly

## Center Time

25 minutes

Students team up and choose one of the games that were just introduced in the previous section. They can start with one and when finished move to the other.  I am going to choose the groups today.  I am going to mix groups by mixed ability with the exception of 2 students.  After looking at some of their previous work with comparing, I want to use this time to reinforce the concept and guide them through the explanation of their thinking process.  After that, I will move to observing the other groups and looking for:

*Do students need to count the dots or do they instantly recognize them?

*What strategies are students using to compare cards.

I will again use my steno pad to keep informal notes.

## Wrap Up: Introducing Oral Story Problems

15 minutes

I am going to end today's lesson by introducing the story problem process with the students.  I will work on solving the problem as a whole group and look for students to be able to explain their thinking throughout the process.  This is a great opportunity to establish the routine for story problems.  Make sure that you have cubes or some kind of counters that can be used as manipulatives.  You can make up any story but keep the numbers small to allow students to focus on making sense of the problem.

My Story:

The other day I went to the Farmer's Market.  I walked around until I found the farmer selling tomatoes that were still on the vine.  I picked up the first bunch of tomatoes and I counted them. There were 4 tomatoes on the vine.  I decided I needed some more and picked up another vine with 2 tomatoes on it.  (I then look at the students and ask:) What happened in the story?

I will then call on several students to tell me what happened in the story.  Even if the first student describes it correctly, i want to get a few voices and focus not on repeating exactly how I said it but rather the general sequence of the story.  I am not looking for an answer yet but rather the ability to retell the sequence.  I then ask the students of there were greater than or less than 4 tomatoes in the story?  I take any answers but I ask students to explain how they know.  Finally I ask, If I took 4 tomatoes and 2 tomatoes, then how many tomatoes did I buy?  The students are adding with in 100 (CCSS.Math.Content.1.NBT.C.4).  The students are adding within 20 in a story problem (CCSS.Math.Content.1.OA.A.1).  I ask them to use cubes to show their answer/thinking.  I will then call on students to share their approaches.  I will model equations for their thinking, pointing out how a mathematician would write it with numbers.  The students are making sense of the problem, and are identifying a starting point to obtaining a solution (CCSS.Math.Practice.MP1).   The modeling with mathematics is a way of introducing CCSS.Math.Practice.MP4.   The students are explaining their thinking and sharing strategies they used to find a solution (CCSS.Math.Practice.MP6).

I repeat this with one or two more tomato stories.  Again focusing on the procedure and not big numbers.