Lesson 3
Count on or Count Back to Subtract
Lesson Purpose
The purpose of this lesson is for students to subtract within 1,000 using strategies that demonstrate an understanding of the relationship between addition and subtraction, including counting on and counting back.
Lesson Narrative
In previous units, students used counting on or counting back to subtract within 100. In this lesson, they analyze different methods, including counting on and counting back, to subtract within 1,000. They make connections between sums of 10 and sums of 100, for example \(5 + 5 = 10\) and \(50 + 50 = 100\). Students use the relationship between addition and subtraction as they find unknown values in subtraction and addition equations.
- Engagement
- MLR8
Learning Goals
Teacher Facing
- Subtract within 1,000 using an understanding of the relationship between addition and subtraction.
Student Facing
- Let’s find the difference between numbers.
Required Materials
Materials to Gather
Required Preparation
CCSS Standards
Addressing
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 20 min |
| Activity 2 | 15 min |
| Lesson Synthesis | 10 min |
| Cool-down | 5 min |
Teacher Reflection Questions
What strategies are students using to subtract? How can you help students see the connections between addition and subtraction as they consider ways to subtract within 1,000?
Suggested Centers
- Five in a Row: Addition and Subtraction (1–2), Stage 6: Add within 100 with Composing (Supporting)
- How Close? (1–5), Stage 3: Add to 100 (Supporting)