Addition Number Sentences

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SWBAT match addition number sentences to the correct number story.

Big Idea

Our little ones love to find out they can write a "sentence" using numbers and symbols. They like to think it is a secret code they are learning. This lesson teaches them to express their problem and answer with an addition sentence.

Rev Them Up

3 minutes

The CCSS provides opportunities for First Graders to solve problems by using addition to join parts together (1.OA.A.1). This lesson supplies that opportunity and builds up the math practice of making sense of problems and persevering in solving them. You want them to share their critical thinking ideas and test ideas to determine outcomes and make connections between numbers. It is important to have them share their knowledge to help them become conscious of what they know. This will help them persevere and continue to take risks while solving (MP1).

At this point, some of my students are still struggling with number sense, so I will make this easier on them by giving them a partner who has solid number sense. This will ensure that everyone is able to concentrate on joining parts together.

I will get them thinking about joining numbers by discussing, modeling, and using the students as a model as we line up for a restroom break. I usually tell my students to line up as a whole group, and they know to get in number order at the door. But I want to make them think a little, so I will mix things up a little and give them the chance to think about joining parts together by stating the following:

  • I need my 4 students at group one to line up. If my 5 students at group two join them, how many people will be in line? (9) Go ahead and line up.
  • I want everyone at group three and four to line up. How many students do we have altogether in groups three and four? (10)
  • How many people do we have in line so far? How can we figure it out? (Count everyone in line) (19)
  • How many students do we need to have join the 19 that are already in line? (3) My last group can line up. How many students do we have altogether when we joined the last 3 with our other 19? (22) How did you figure that out? (I counted up, I counted everyone in line, I knew we had 22 kids in our class and no one is absent)

Whole Group Interaction

15 minutes

I have a set of red and blue unifix cubes.  These are the only colors I will use and you can use any two colors you pick or have the most of.  I am using two colors to represent two different parts of my problem. 

I will also have a brown bag and a 3x5 card for every set of partners in my room.  These are just plain lunch bags or you can use any type of container you wish.  I will not pass out partner supplies until I am finished with the demonstration.

I will begin this activity at our gathering place with them sitting on the carpet in their spots.  I find that it is always better to assign them their own spot at the carpet at the beginning of the year to prevent arguing or socializing with their best buds.

I will place 5 red and 5 blue unifix cubes in the brown bag and shake them up.  I will make sure to have a pencil and 3x5 card close by also. I will ask the students:

If I reach in and take out a handful of cubes, some of them will be red and some will be blue.  Can I use math to figure out how many I took out in all?

You want your students to respond with: "yes, you can use addition" or something along those lines.

I will reach in and pull out a handful.  I will connect them together according to their colors.  I will ask the students to help me use addition to find out how many I pulled out in all.  As they count and interact with me I will show them how I can write the problem onto my 3x5 card using a number sentence.

I will unsnap my cubes and drop them back into the bag and do it again.  I will repeat this process with four other examples for my students to understand the procedure thoroughly.

When I know they all understand the game at hand, I will divide them up into partners and pass out supplies.  I would suggest warning them in advance that the cubes never go above our armpits.  When we pull them out of the bag and put them on our desk or floor (depending on where they are working) there is no tossing or throwing.  They love to get carried away when cubes are involved.  Their goal is to create 5 different number sentences, so they should pull from their bag at least 5 different times.

I will be walking around and monitoring progress to check for understanding while my students are completing their task.  This activity is a very concrete one.  The process is an important one for them to participate in so that they can understand word problems in later lessons. Also, they will be able to connect to their prior knowledge and be better able to develop mental pictures of items joining together to solve word problems.

Independent Practice

20 minutes

I will be using my Number Sentence Match-Up printable workbook for students in this lesson.  I created several story problems and their matching number sentences.  Students will have to cut them apart, match them correctly and then glue them inside their workbook.  Directions are included in the file.

Here is a student matching her number sentence to a story problem.

When you view the file you will notice the word problems are written with as few of words as possible and as simple as possible.  I tried to stick with sight words and words that were easily sounded out.  I did this to allow my students who are reading at lower levels to be able to fully engage in  the lesson and concentrate on the math at hand and not so much the reading.

Also, you will notice the first four number sentences are completely written out and the students just match the correct sentence to the word problem, but then the last two word problems contain a blank number sentence framework for them to fill in the missing numbers. 


5 minutes

I will post this word problem on the Smart Board:

3 boys came in the room. 2 girls came in the room. How many are there in all?

3+2=5 or 2+3=5

Which sentence is correct or are they both correct?

This will stimulate a discussion with my class concerning part+part=whole and the Commutative Property, which we will learn more about in a later lesson. I want them to note two things:

  • They are both correct because they are using the correct parts and just switching positions (Commutative Property).
  • The first sentence is an exact match to the word problem because the numbers appear in the order they are in the story.