Lesson 8

Solve Word Problems

Est. Class Sessions: 3

Developing the Lesson

Part 1: Use Tools to Solve and Show Problems

Use Ten Frames, Number Lines, and Part-Whole Diagrams. Read and show students the problem about monkeys and lions you have written on the display of the Show a Word Problem Master. Have 20 connecting cubes available for each student. After students have had a chance to think about the problem, ask different students to show how to use each representation (ten frames, number lines, and part-whole diagrams) to solve the problem posed. See Figure 1.

  • What is the problem? (Possible response: I need to figure out how many animals there are altogether.)
  • How did you decide where to put the numbers in the part-whole diagram? (Possible response: The problem is about 2 parts being put together so I put the parts in small boxes to then make a larger whole.)
  • How can the number line help you solve the problem? (Possible response: The number line helps keep track of the numbers as I counted on.)
  • How can the ten frame help you solve the problem? (Possible response: The ten frame helps me see the fives and tens. When adding 8 and 4, I could see the ten and knew the answer was 2 more than 10.)
  • Did anyone use a different tool or strategy? What did you use? (Possible response: I used connecting cubes to act out the problem and then counted all the cubes; I did not need to use any tools. I know 8 + 4 = 12.)

Continue the discussion with the fish bowl question you prepared on the display of the Show a Word Problem Master. See Figure 2.

  • What is the problem? (Possible response: I need to figure out how many fish are green.)
  • How did you decide where to put the numbers in the part-whole diagram? (Possible response: In this problem, the whole is given so I put 11 in the "whole" box and one of the parts in the smaller boxes. I needed to find the other part.)
  • How can the number line help you solve the problem? (Possible response: The number line helps keep track of the numbers as I counted up from 5 to 11. I then went back and counted the hops.)
  • How can the ten frame help you solve the problem? (Possible response: I filled in 5 and could "see" the 11 and knew that I needed 5 and 1 or 6 to make 11.)
  • Did anyone use a different tool or strategy? What did you use? (Possible response: I know 5 + 5 = 10 so 5 + 6 = 11. I did not use any of the tools; I used connecting cubes to act out the problem. I counted 5 and kept adding cubes to 11 and then counted the cubes that I added.)

Students used these tools throughout First Grade. This quick review on how to use ten frames, part-whole diagrams, and number lines to solve addition and subtraction problems may be sufficient. These tools support student reasoning and explanation of their reasoning. Create additional problems if students need a more extensive review of these tools.

Explain to students that they can use more than one tool or strategy to solve each problem and that they are not limited to the ten frames, number lines, and part-whole diagrams. It is important to ask students to explain their thinking and help students who have misconceptions about the correct ways to use tools and strategies. Use Sample Dialog 1 to guide your discussion of using tools to solve problems.

Use the sample dialog to guide your discussion of the sample subtraction problem:

There are 11 fish in a bowl. Five of the fish are orange and the rest are green. How many are green?

Teacher: Who can explain how to solve the problem?

Michelle: I used the number line. I started at 11 and counted back 5: 11, 10, 9, 8, 7. The answer is 7.

Teacher: Does everyone agree that 7 is the answer?

Ana: I didn't get 7. I got 6. I used the number line, too, and I counted back 5: 10, 9, 8, 7, 6. My answer is 6. When you use the number line you have to count the hops or the spaces. You start at 11 and the first hop is back to 10. Four more hops and you land at 6.

Teacher: Good thinking, Ana! It is important to count the hops on the number line, so that you get the correct answer. Did someone use a different strategy or tool?

Sam: I put 11 connecting cubes in one of the "part" boxes on the part-whole diagram. I put 5 cubes in the other "part" box. Then I put them together in the "whole" box and I got 16.

Teacher: Let's think about your answer. Does it make sense?

Roberto: That doesn't make sense. There are 11 fish in the bowl. That number should go in the "whole" box. Then move 5 to the "part" box because 5 of the 11 fish are orange. The rest of the fish are green. There are 6 cubes left, so 6 are green.

Teacher: Great, Roberto! It's important to look back at the problem and see if your answer makes sense.

Practice Using Tools to Solve Word Problems. Direct students to the Solve Word Problems pages in the Student Activity Book. Tell students that they will work with a partner to solve four problems in different ways. Refer students to a display of the Math Practice page.

  • Which of these practices have we been focusing on? (Possible response: Math Practice 2, Find a strategy, and Math Practice 5, Show my work.)

Refer students to Math Practice 1, Know the problem.

  • What can you do to figure out what the problem is asking? (Possible response: Draw a picture of the problem, act out the problem with my partner or with the connecting cubes, underline the question, find the information I need to answer the question.)
  • Record student ideas on the board. See Figure 3.
  • These problems are about ants, elephants, monkeys, and dogs. What can you do if you do not know a word in a problem? (Possible response: Read through the word and see if you can figure out what the word is or might be; replace the word with a word you know that makes sense; act out the words you know to help you figure out the words you do not know.)

Direct students to work with a partner to answer Questions 1–4. While students are working, circulate around the room. Listen to students' strategies and note their confidence with various tools. Also make note of how confidently students know the problem they are solving. Choose one student pair to show how to solve each of Questions 1–3. Provide them with a display of the Show a Word Problem Master to show their work. When most students are ready, ask the chosen student volunteers to demonstrate their solutions and explain how they used the tools to solve the problem.

Use a display of the Show a Word Problem Master to capture how Carla used the part-whole diagram in Question 4. Ask students to use their thumbs to show if they agree with Carla. Show a thumbs-up if they agree and thumbs-down if they do not agree.

  • What might you say or ask Carla to help her? (Possible response: How can the whole be larger than the part? What number would you add to 17 to make 8? Does that make sense?)

Ask students to share their ideas and then ask a student to solve the problem on the display using each of the tools shown.

  • Does anyone have another strategy for this problem? (Possible responses: I know 8 + 8 = 16 so 8 + 9 = 17. So there were 9 dogs adopted; I counted back from 17 to 8 and there were 9 hops.)
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Showing 8 + 4 with a part-whole diagram, ten frames, number line, and number sentence
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Showing 5 + = 11 with a part-whole diagram, ten frames, number line, and number sentence
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A sample list of student generated strategies for knowing the problem
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