Lesson 9
Add 2 Two-digit Numbers
Lesson Purpose
The purpose of this lesson is for students to add 2 two-digit numbers within 100 in any way that makes sense to them, including composing a ten.
Lesson Narrative
In previous lessons, students added a one-digit number and a two-digit number with composing a ten. They also added 2 two-digit numbers without composing a new ten. They discussed methods based on place value and the properties of operations. They wrote equations to show their thinking.
In this lesson, students add 2 two-digit numbers in any way that makes sense to them. Students may apply methods learned in previous lessons, including methods based on making a new ten or adding tens and tens and ones and ones. Students are not required to write equations, although some may do so.
- Action and Expression
- MLR7
Learning Goals
Teacher Facing
- Add 2 two-digit numbers within 100, with composing a ten, in a way that makes sense to them.
Student Facing
- Let’s add two-digit 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
How effective were your questions in supporting students’ thinking today? What did students say or do that showed they were effective?