Double Trouble: Subtraction Practice
Students will be able to accurately subtract two digit problems with regrouping.
Introduction (5 minutes)
- Use a real life situation that students are familiar with to explain regrouping. For example, if students’ desks are organized in rows, ask: I need 8 students to help me deliver items to other classrooms, but I only have 6 students seated in a row. How can I solve that problem?
- Explain that subtraction with regrouping is very similar, where part of the next row must be moved to the first row to have what is needed.
Explicit Instruction/Teacher Modeling (5 minutes)
- Pair students up.
- Explain to students that they will be working with subtraction, but these problems will require decomposing, or breaking big numbers into smaller numbers, or regrouping, which is rearranging numbers.
Guided Practice/Interactive Modeling (10 minutes)
- Provide some sample subtraction with regrouping problems on the dry erase board.
- Have students show their work on paper with the necessary manipulatives they have for support.
- Instruct your students to explain to the class the need for certain steps as the problems are being worked out.
- Sample problems should be tailored to fit the level of the students. For example, easier problems could include 44-37, 25-19, and 31-26, medium level problems could include 44-27, 75-39, and 61-18, difficult problems could include 125-19, 144-27, and 161-18, and advanced problems could include 125-119, 144-127, and 161-118.
Independent Working Time (15 minutes)
- Pass out the game sheets (Math Go Round) and the necessary materials.
- Review the rules on the game sheets with the students.
- Monitor the students as they play, and provide support as needed.
- Enrichment: Assign a game sheet at a more challenging level.
- Support: Write problems in a place value chart for students. Give students manipulatives to help them see physical evidence of subtraction.
Assessment (5 minutes)
- Have each student pick out a domino and draw the dots from the domino on the assessment.
- Direct your students to write a subtraction problem using the numbers given and solve this problem.
- Ask your students to check this problem.
Review and Closing (5 minutes)
- Have a discussion with your students. Potential guiding questions include: What does it mean to decompose? When would you need to decompose? When would you not need to decompose?
- Instruct your students to create illustrations on the board to help them in their explanations.