Tell students, “We have been practicing adding and subtracting. Now we are going to add and subtract to solve problems.” Remind students that they have counters to use as they need them.
Say this word problem aloud: “Bennett caught 5 fish. His mom caught 3 fish. How many fish did they catch in all?”
Ask students to use their counters to model the problem. “How many fish did Bennett and his mom catch in all?” (8) Ask a student to show how s/he solved the problem.
“What number sentence can we write for this problem?” (5 + 3 = 8) “Why do we use addition? Why is this not a subtraction problem?”
Ask students to turn and talk with a partner, then share their ideas with the class.
It is important to continually emphasize that addition puts sets of objects together and subtraction takes them apart. Helping students identify the appropriate operation in word problems is one of the most critical steps to supporting their success.
Say this word problem aloud: “Ellery had 6 markers. She gave 1 to Ayden. How many markers does Ellery have left?” (5) Ask several students to show how they solved the problem. Students should use the counters to model the situation. “What number sentence can we write for this problem?” (6 − 1 = 5) “Why do we use subtraction? Why is this not an addition problem?” Again ask students to verbalize that Ellery gave some markers away, so this is a subtraction problem. For a visual, draw 6 markers on the board and put a large X over the one that she gave to Ayden. This helps students see the 6, 1, and 5 in the number sentence.
Say this word problem aloud: “6 boys were playing in the park. 3 girls were playing in the park. How many girls and boys were playing in the park in all?” Ask students to draw a picture to solve this problem. “What number sentence can we write to represent this problem?” (6 + 3 = 9) “Why is addition used to solve this problem? Why is subtraction not used?”
Say this word problem aloud: “Seven children were playing in the park. Three children went home to eat lunch. How many children were left playing in the park?” Ask students to draw a picture to solve this problem. “What number sentence can we write to represent this problem?” (7 − 3 = 4) “Why is subtraction used to solve this problem? Why is addition not used?”
Write the number sentence 4 − 3 = 1 on the board. Tell students a story that corresponds to this number sentence. Ask students to use their counters to act out your story, so they are sure it corresponds. Now ask students to tell stories that correspond to this number sentence. If students are struggling, suggest a topic that they enjoy such as boats, kittens, etc. After each story is told, ask students to model the story with counters to confirm that it does correspond to the number sentence.
Write the number sentence 1 + 8 = 9 on the board. Tell students a story that corresponds to this number sentence. Ask students to model the number sentence with counters. Ask students to tell stories corresponding to this number sentence, and have the other students model each story with counters.
Distribute the Addition and Subtraction Word Problems sheets (M-K-3-3_Addition and Subtraction Word Problems and KEY.docx) to students. Ask students to write the corresponding number sentences for each problem.
Extension:
Use the activities and strategies listed below to tailor the lesson to meet the needs of your students.
- Routine: Regularly put a number sentence using addition or subtraction on the board. Ask students to tell a story that corresponds to the number sentence.
- Remediation: If students struggle with translating word problems to number sentences, help students model the action of the word problems. While modeling the action, be purposeful in emphasizing the meanings of addition and subtraction so students can learn to differentiate between these operations.
- Small Group: Give each person in a small group a number sentence. Ask each student to tell the rest of the group a story that corresponds to his/her number sentence. The rest of the students in the group should model the word problem using counters and verify that the word problem corresponds to the number sentence.
- Expansion: Have students create a book that includes their own word problems. Students can create word problems for given number sentences and then use drawings to solve the problems.
