# Lesson 12

School Supplies

### Lesson Purpose

The purpose of this lesson is for students to solve Compare, Difference Unknown story problems in a way that makes sense to them.

### Lesson Narrative

Students build on representations and methods they learned in the previous lesson, in which students compared different quantities of connecting cubes. In this lesson, students work with comparisons in story contexts. The first activity uses the Three Reads routine to help students better understand the story problem and how the quantities are related.

As students explain their thinking, write equations to support connections between comparing and addition and subtraction. Include a box around the difference in the equations.

• Representation
• MLR7

### Learning Goals

Teacher Facing

• Relate counting to addition and subtraction.
• Solve Compare, Difference Unknown story problems in a way that makes sense to them.

### Student Facing

• Let’s find the difference between quantities.

Addressing

Building Towards

### 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

How effective were your questions in supporting students’ thinking today? What did students say or do that showed they were effective?

### Print Formatted Materials

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### Additional Resources

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