Unit 5, Lesson 10
Decenas y decenas, unidades y unidades
Grado 1
Preparation
Lesson Narrative
In the previous lesson, students added 2 two-digit numbers with composing a ten, in a way that made sense to them. This lesson focuses on adding tens and tens and ones and ones. This method is important because it sets students up to add multi-digit numbers in later grades. Students apply what they learned about the commutative and associative properties to see that it doesn’t matter if they add tens and tens first or ones and ones first.
- Representation
- MLR2
- Interpret (orally) diagrams that represent a strategy for adding 2 two-digit numbers within 100 by place.
- Sumemos números de 2 dígitos.
Required Materials
Activity 3
Required Preparation
- Create 2 separate posters that show base-ten drawings of 34 and 57. Leave space to write equations underneath the drawings.
- Each group of 2 needs one set of digits (0–9) from the Number Puzzle Digit Cards from a previous stage of this center.
Suggested Centers
NoneTeacher Reflection Questions
In what ways does the work of this lesson lay the foundation for student understanding of the standard algorithm for addition, which will be used in later grades?