# Lesson 5

Patterns with Even and Odd Numbers (optional)

### Lesson Purpose

The purpose of this optional lesson is for students to notice and describe patterns in sums within 20 using what they know about even and odd numbers.

### Lesson Narrative

In previous lessons, students worked with physical objects and images to determine if groups of objects were even or odd. They represented even numbers as an equation with two equal addends.

In this lesson, students continue to practice identifying and justifying even and odd numbers and deepen their number sense with numbers within 20. They notice patterns in even and odd numbers when counting and use what they know about 2 equal groups and pairs to generalize why adding 1 changes whether a group is even or odd, but adding 2 does not (MP8). Students add even and odd numbers and connect the mental strategies they use to add within 20 to patterns in the value of the sums of even and odd addends.

This lesson is optional because it goes beyond the depth of understanding required to address the standards.

• Representation
• MLR2

### Learning Goals

Teacher Facing

• Recognize patterns in sums of odd and even numbers.

### Student Facing

• Let’s look for patterns with even and odd numbers.

### Required Materials

Materials to Gather

Materials to Copy

• Presto Chango Recording Sheet

### Lesson Timeline

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

### Teacher Reflection Questions

How did students use what they have learned about even and odd numbers to explain the effect of adding 1 or 2? How did students show what they understand about numbers that can be decomposed into 2 equal groups or can be made into pairs? How can you build on that understanding as students consider other equal groups in the next section?

### 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)

### Print Formatted Materials

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