Unit 2, Lesson 4
A Change Unknown
Grade 1
Preparation
Lesson Purpose
The purpose of this lesson is for students to interpret a strategy for solving an Add To, Change Unknown problem that involves using drawings to count on. Students use strategies that make sense to them to determine the number that makes an equation true.
Lesson Narrative
In previous lessons, students represented Add To story problems including problems where the change was unknown. Students compared different ways to determine an unknown, including counting on. In this lesson, students make sense of a way to represent counting on from one number to another in the context of a Add To, Change Unknown story problem. Students are then invited to use strategies that make sense to them to determine the number that makes an equation true.
In this lesson, students revisit the meaning of an equation, which is first introduced in IM Kindergarten as a way to represent story problems when all quantities are known. Students are not expected to write equations on their own until Section D of this unit, but students may begin to try writing equations on their own before then.
- Representation
- MLR8
- Comprehend the notation “
” can be used to represent an unknown in an equation. - Explain (orally) strategies for finding the value of an unknown addend, including counting on.
Required Materials
Required Preparation
None
Suggested Centers
NoneTeacher Reflection Questions
Reflect on points during the lesson when you learned the most about your students’ thinking. What structures or questions helped you focus on learning about your students? How will you use what you learned in an upcoming lesson?
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