# Lesson 1

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### Lesson Purpose

The purpose of this lesson is for students to arrange a number of objects into 2 equal groups and learn that some numbers of objects can be put into two equal groups without any objects left over.

### Lesson Narrative

In this lesson, students learn that some numbers of objects can be split into two equal groups, without any objects left over, and other numbers cannot. The work of this lesson builds on students’ real-world experiences with equal sharing and prepares them to understand and use the terms even and odd to describe groups of objects in future lessons (MP6). In the first activity, students separate objects into 2 equal groups and begin to create a list of numbers that can be split into 2 equal groups. In the second activity, they are given access to objects, but are also encouraged to consider other representations of numbers, including equations, that may show a number of objects as 2 equal groups or 2 equal groups and 1 leftover.

Students should have access to objects (connecting cubes or counters) throughout the lesson, including the cool-down.

• Action and Expression

### Learning Goals

Teacher Facing

• Determine whether a group of objects can be arranged into 2 equal groups.

### Student Facing

• Compartamos equitativamente grupos de objetos con un compañero.

### Required Materials

Materials to Gather

### Required Preparation

Activity 1:

• Each group of 2 needs a container of counters with 4 to 15 counters in each container. These containers will be used again in the next lesson.
• Create a t-chart on a large piece of chart paper to display in the activity synthesis.
• Use “Two Equal Groups” as the title.
• Label the t-chart with “no leftovers” and “some leftovers” as the categories.

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 20 min Activity 2 15 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

What ideas did students already have about the number of objects that can be made into equal groups? How did you elicit and use these ideas during the lesson?

### Suggested Centers

• Target Numbers (1–5), Stage 7: Subtract Hundreds, Tens, or Ones (Supporting)
• Five in a Row: Addition and Subtraction (1–2), Stage 8: Add within 1,000 with Composing (Supporting)
• How Close? (1–5), Stage 4: Add to 1,000 (Supporting)