Lesson 6
Compare Methods for Subtraction
Lesson Purpose
The purpose of this lesson is for students to compare methods for subtracting a one-digit number from a two-digit number with and without decomposing a ten.
Lesson Narrative
In the first activity, students consider 3 methods for finding the difference represented using base-ten diagrams. In the second activity, students find the difference with and without decomposing a ten and represent their thinking using base-ten diagrams, words, or equations. Students are not expected to draw their work with base-ten diagrams in a specific way. Students should have access to base-ten blocks throughout the lesson and the cool-down. Students compare their methods, and the teacher records student thinking using base-ten diagrams and equations in the activity synthesis. In the lesson synthesis, students consider different ways to represent decomposing.
- Representation
Learning Goals
Teacher Facing
- Describe how methods of subtraction are the same and different when subtracting a one-digit number from a two-digit number.
Student Facing
- Let’s compare subtraction methods.
Required Materials
Materials to Gather
Materials to Copy
- Target Numbers Stage 4 Recording Sheet
Required Preparation
Activity 2:
- Remove 0 and 10 from each set of cards (or prompt students to remove them) before the activity.
CCSS Standards
Addressing
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 15 min |
| Activity 2 | 20 min |
| Lesson Synthesis | 10 min |
| Cool-down | 5 min |
Teacher Reflection Questions
In upcoming lessons, students will subtract two-digit numbers from two-digit numbers with and without decomposing a ten. What do students need to understand about place value in order to use strategies that would require decomposing when subtracting by place?
Suggested Centers
- Capture Squares (1–3), Stage 3: Add within 20 (Addressing)
- Five in a Row: Addition and Subtraction (1–2), Stage 6: Add within 100 with Composing (Addressing)
Print Formatted Materials
Teachers with a valid work email address can click here to register or sign in for free access to Cool Down, Teacher Guide, and PowerPoint materials.
| Student Task Statements | docx | |
| Lesson Cover Page | docx | |
| Cool Down | Log In | |
| Teacher Guide | Log In | |
| Teacher Presentation Materials | docx | |
| Blackline Masters | zip |