# Lesson 25

How Do You Want to Subtract?

### Lesson Purpose

The purpose of this lesson is for students to use subtraction methods flexibly to find differences.

### Lesson Narrative

Students apply their learning from the unit to flexibly use methods to subtract within 20. There is not one correct method to use, as it is based on each individual student's understanding of the concepts of subtraction and their known facts. It is helpful for students to listen to and make sense of others’ reasoning about which method they used (MP3). In the first activity, students find differences given expressions. In the second activity, students apply subtraction methods as they solve story problems with the unknown in all positions.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Use subtraction methods flexibly to find differences based on the numbers in a given problem.

### Student Facing

• Let’s use subtraction methods that work for the numbers in a problem.

### Required Materials

Materials to Gather

### 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

How did your students represent their work today? How might you support them in creating more efficient representations?

### Print Formatted Materials

For access, consult one of our IM Certified Partners.