# Lesson 4: The Power of 10

## Getting Started

### Questions to Explore

• How do patterns help us in math?
• What is the pattern when counting up or back by 10s?

### Skills

• Mentally add 10 or 100 to a given number 100-900, and mentally subtract 10 or 100 from a given number 100-900
• Make sense of problems and persevere in solving them
• Model with mathematics

### Materials

• abacus (kit)
• calendar
• index cards (kit)
• Interactive Notebook
• laminated number grids (kit)
• number cards (kit)

### Introduction

Materials: Interactive Notebook
In this lesson, your child extends her skill with counting by 10s to being able to count up and back by 10s from any number. Begin by asking your child to count to 100 by 10s.

Refer back to Lesson 2 Activity 3. Ask: What numbers did you color when you were counting by 10s? Listen for "I colored all the numbers under 10 on the grid" and "I colored all the numbers that end in 0." Your child may need to refer back to her number pattern book in her Interactive Notebook.