Addition Word Problems

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Objective

SWBAT solve two digit addition word problems using the draw a picture strategy.

Big Idea

In this lesson students use the strategy of drawing a picture to solve two-digit word problems.

Activating Strategy

10 minutes

To begin this lesson, we play the following game on the SmartBoard:

Adding with tens and ones.

One way that I like to keep my students engaged is by putting them in pairs and give each pair a personal white board.  When the question comes up on the SmartBoard, then each pair is given the opportunity to discuss the answer and put their answer on their white board.  I then call on random students or pairs of students to come to the board and answer the question.

After the game, we access prior knowledge by having partners add two-digit numbers. I write random two digit numbers on the board for students to add.

Problem-solving lessons can be rich opportunities for building critical thinking skills.  For each problem, I ask a volunteer to present his or her solution and explain the reasoning for each step that was used. After the presentation, I elicit comments or questions from other children. Then I ask if anyone used a different way to solve the problem. I have that child present his or her work and follow up with another class discussion. I continue the presentations and discussions as both opportunity and time permit. (MP3)

NBT.C4 calls for students to use concrete models, drawings and place value strategies to add and subtract within 100.  In this lesson, students will be using a combination of drawing a picture and knowledge of place value to answer the word problems.

Teaching Strategies

15 minutes

I start this lesson by writing the following word problem on the board/chart paper (Addition word problems also available):

Kelly has 23 toy cars.  He gets 6 more new toy cars.  How many toy cars does he have now?

I start by asking the questions:

  • What information do we need to find out?  (How many toy cars he has now.)
  • What information do we have? (He has 23 and he gets 6 more new cars.)
  • How can we draw a picture to show how many toy cars he has now? (I can draw 2 lines for 2 tens and 3 circles for 3 ones.)
  • How can we draw a picture to show how many new toy cars he gets? (I can draw 6 circles for 6 ones.)

Model how to add the ones first, and add the tens. 

I then give students base ten blocks, or paper to have them model how to solve the problem with me.  Write this problem on the board/chart paper:

Amy picks 60 blueberries to make a pie.  Then she picks 12 more to eat.  How many blueberries does she pick?

  • What information do we need to find? (How many blueberries she picked.)
  • What information do we need to use? (She picked 60 blueberries and then 12 more blueberries.)
  • How can we draw a picture to show how many blueberries she picked?  (I can draw 6 lines for 6 tens.)
  • How can we draw a picture to show how many blueberries she eats? (I can draw 1 line for 1 ten, and 2 circles for 2 ones.)

Have students draw their pictures and solve the problem.

In this picture, the student is demonstrating how to write the numbers in a vertical alignment and drawing a line between the tens and ones place.  Many of my students use this strategy to help them with adding the ones place first.  

 

Independent Practice

30 minutes

For the independent practice portion of this lesson, I assign Addition Word Problems_worksheet. for students to complete.  

 

For struggling students, I provide them with base ten blocks to help them solve the problems instead of drawing pictures.  

Closing/Summarizing

5 minutes

To close out the lesson, I have students pick a number from each column:

Column A

Column B

10

15

20

28

30

37

40

49

I then have them write their own word problem using those two numbers.  We then mix, pair, share to solve our word problems.

(I have them pick a number from each column instead of creating their own to ensure that the numbers that we are adding do not require regrouping.)