Getting Wordy with Subtraction
Students will be able to explain how to solve a subtraction word problem. Students will be able to illustrate subtraction word problems. Students will be able to solve written subtraction word problems.
Introduction (5 minutes)
- Show class the What's Missing? Subtraction Song to introduce the topic.
- Tell students that they will be learning how to solve subtraction word problems.
- Remind the class that subtraction is taking away one amount from another amount.
Explicit Instruction/Teacher Modeling (20 minutes)
- Write the steps of solving a subtraction story problem on the board on the whiteboard. For example: Circle the numbers, underline the question, solve the number sentence, and answer the question (CUSA).
- Explain each step to the class. For example: Circle the numbers: Circle the numbers they see to choose what numbers will be used in their subtraction number sentence. Underline the question: Underline the question to find clue words telling to subtract. Note clue words such as left, take away, less than, and remain. Solve the number sentence: Use the minus and equal sign to solve the problem. Answer the question: Use a complete sentence to answer the question.
- Sing the following subtraction story song to the tune of Sally the Camel with the class to help them remember the steps: First, we circle the numbers (x3) to solve a word problem. Second, we underline the question (x3) and find the clue words. Third, we solve the number sentence (x3) using the minus and equal sign. Fourth, we answer the question (x3), and then we are complete! How neat.
Guided Practice/Interactive Modeling (10 minutes)
- Write a subtraction story problem on the board. For example: A farmer had 4 chickens, and 2 ran away. How many chickens are left?
- Call up enough students to illustrate the problem.
- Solve the problem with the class, saying aloud the steps and performing them.
- Repeat with another subtraction story problem and different students.
Independent Working Time (15 minutes)
- Tell the class that they will show word problems with counters.
- Demonstrate how they will read the problem and use the counters to find the answers.
- Give each student enough counters to solve the problems.
- Write a problem on the board.
- Monitor students as they work on illustrating the problem.
- Ask various students how they got their answers.
- Enrichment: Give the advanced students more difficult problems to illustrate with their counters. For example, give them problems with larger numbers for more of a challenge. Place additional word problems on the board and have these students complete them on the other side of their worksheets. Give them the second Math Subtraction worksheet to practice.
- Support: Give your students counters to use as they complete their worksheets.
Assessment (10 minutes)
- Give each student a Math Subtraction worksheet to complete.
- Check students' answers to measure understanding.
Review and Closing (5 minutes)
- Sing What's Missing? Subtraction Song with the class again.
- Place a subtraction story problem on the board.
- Have the students walk you through how to solve it.