# Lesson 11

Solve Problems Involving Time (Part 2)

### Lesson Purpose

The purpose of this lesson is for students to solve problems involving addition and subtraction of time intervals in minutes.

### Lesson Narrative

In this lesson, students use any strategy and representation to solve problems involving elapsed time. The problems involve unknowns in all positions: start time, end time, and duration. When students recognize the mathematical features of familiar real-world objects and use those features to solve problems, they model with mathematics (MP4).

• Representation
• MLR8

### Learning Goals

Teacher Facing

• Solve problems involving addition and subtraction of time intervals in minutes.

### Student Facing

• Let’s solve more problems involving time.

### Required Preparation

Activity 1:

• Display students’ ideas from the lesson synthesis in the previous lesson.

### 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

Who got to do math today in class and how do you know? Identify the norms or routines that allowed those students to engage in mathematics. How can you adjust these norms and routines so all students do math tomorrow?

### Suggested Centers

• Number Puzzles: Addition and Subtraction (1–4), Stage 5: Within 1,000 (Supporting)
• Target Numbers (1–5), Stage 7: Subtract Hundreds, Tens, or Ones (Supporting)