# Lesson 1

Contemos 2 grupos de objetos

### Lesson Purpose

The purpose of this lesson is for students to count 2 groups of objects to find the total, within 10.

### Lesson Narrative

In a previous unit, students counted groups of up to 10 objects, recognized and wrote numbers 1–10, and connected numbers to quantities. In this lesson, students are introduced to addition as they count to find the total of 2 groups. Many students may approach these activities the same way that they answered “how many” questions in previous units—by putting the 2 groups of objects together and then counting all of the objects. The syntheses focus on different strategies for finding the total number of objects given 2 groups of objects.

The language “add,” “adding,” and “put together” is used throughout the lesson. Students are not expected to produce this language until later in the unit. The notation “_____ and _____” is introduced by the teacher in Activity 2 as one way to represent combining the 2 groups. Students need time to see and hear teachers using this notation and other addition language before they can understand the more abstract language of “plus” or an expression “_____ + _____” which will be introduced in a later section. Putting together two groups of objects to determine the total prepares students for work in a future unit in which they will represent and solve Put Together, Total Unknown story problems.

• Action and Expression
• MLR8

### Learning Goals

Teacher Facing

• Count to find the total number of objects given 2 groups of objects, up to 10.

### Student Facing

• Descubramos cuántos objetos hay en dos grupos.

### Required Materials

Materials to Gather

### Required Preparation

Activity 1:

• Each group of 2 needs a bag of up to 10 pattern blocks with a mix of squares and triangles.

Activity 2:

• Each student needs a tower with up to 5 connecting cubes.

Activity 3:

• Gather materials from:
• Math Libs
• Match Mine

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 10 min Activity 2 10 min Activity 3 25 min Lesson Synthesis 5 min Cool-down 0 min

### Teacher Reflection Questions

Which centers from previous units can be used to support students in practicing counting groups of objects?