Unit 2, Lesson 6
Comparemos métodos de resta
Grado 2
Preparation
Lesson Narrative
In the first activity, students consider 3 methods for finding the difference represented using base-ten diagrams. In the second activity, students find the difference with and without decomposing a ten and represent their thinking using base-ten diagrams, words, or equations. Students are not expected to draw their work with base-ten diagrams in a specific way. Students should have access to base-ten blocks throughout the lesson and the Cool-down. Students compare their methods, and the teacher records student thinking using base-ten diagrams and equations in the Activity Synthesis. In the Lesson Synthesis, students consider different ways to represent decomposing.
- Representation
None
- Compare and contrast (orally) strategies and recording methods for subtracting a one-digit number from a two-digit number.
- Describe (orally) how a base-ten diagram and equations represent the same subtraction strategy.
- Comparemos maneras de restar.
Required Preparation
- Remove 0 and 10 from each set of cards (or prompt students to remove them) before the activity.
Teacher Reflection Questions
In upcoming lessons, students will subtract two-digit numbers from two-digit numbers with and without decomposing a ten. What do students need to understand about place value in order to use strategies that would require decomposing when subtracting by place?