# Lesson 19

Formemos números de dos dígitos

### Lesson Purpose

The purpose of this lesson is for students to represent a two-digit number in more than one way, using tens and ones.

### Lesson Narrative

In a previous unit, students decomposed numbers to 20 in different ways. In previous lessons, students learned about the meaning of the digits in a two-digit number. They interpreted, used, and connected different base-ten representations for two-digit numbers including connecting cubes in towers of 10 and singles, base-ten diagrams, addition expressions, and written numbers.

In this lesson, students represent two-digit numbers in more than one way based on place value. Students learn that there are different ways to represent a two-digit number with tens and ones which will be important in a later unit when they compose a ten to add within 100.

• Action and Expression
• MLR7

### Learning Goals

Teacher Facing

• Understand that a two-digit number can be represented in different ways using tens and ones.

### Student Facing

• Formemos números de dos dígitos con decenas y unidades de diferentes maneras.

### Required Materials

Materials to Gather

### Required Preparation

Activity 1:

• Each group of 3-4 needs a bag of connecting cubes in 5 towers of 10 and 4 or 5 handfuls of singles.

Activity 3:

• Gather materials from previous centers:
• Greatest of Them All, Stage 1
• Get Your Numbers in Order, Stage 1
• Grab and Count, Stage 2

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 10 min Activity 3 15 min Lesson Synthesis 10 min Cool-down 0 min

### Teacher Reflection Questions

In the next unit, students add within 100, including adding numbers that require composing a new ten when adding by place. How will the work of this section prepare students for the upcoming work with addition?