# Lesson 4

One More and One Less (optional)

### Lesson Purpose

The purpose of this lesson is for students to use their knowledge of the count sequence to determine one more and one less than groups of objects and numbers.

### Lesson Narrative

In a previous lesson, students used their knowledge of the count sequence to solve story problems involving adding and subtracting one. In this lesson, students apply this understanding to determining one more and one less than a given group of objects or numbers without a context. Students practice counting out a given number of objects. When determining one more or one less, students may recount their collection from 1 or may use their knowledge of the count sequence to know what 1 more or 1 less is. This lesson is optional because the standards do not require students to compare groups of objects or written numbers beyond 10.

If students need additional support with the concepts in this lesson, refer back to Unit 2, Section D in the curriculum materials.

• Action and Expression
• MLR8

### Learning Goals

Teacher Facing

• Count out a group of up to 20 objects.
• Use knowledge of the count sequence to add and subtract one and determine one more and one less.

### Student Facing

• Let’s find 1 more or 1 less.

### Required Materials

Materials to Gather

Materials to Copy

• Number Mat 1-20
• One More, One Less Mat

### Required Preparation

Activity 1:

• Each group of 2 needs 1 connecting cube and at least 20 two-color counters.

Activity 2:

• Each group of 2 needs the number mat, two-color counters, and the connecting cube from the previous activity.
• Each group 2 also needs crayons and a copy of the 1 more, 1 less mat.

Activity 3:

• Gather materials from:
• Less, Same, More
• Math Fingers
• Tower Build
• Math Stories
• Which One

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 15 min Activity 3 15 min Lesson Synthesis 5 min Cool-down 0 min

### Teacher Reflection Questions

Look for students you have not observed doing items on the Section A checklist. Identify opportunities to observe these students in the next lesson.