# Lesson 8 Ten as a Unit

Let’s explore teen numbers.

## Warm-up Which One Doesn’t Belong: Groups of 10

Which one doesn’t belong?

## Activity 1 Counting Collections: Count and Show How Many

Your job is to figure out how many cubes are in the bag.

## Activity 2 Building Teen Numbers

Choose 4 numbers to represent.

Circle them.10

11

12

13

14

15

16

17

18

19

Use connecting cubes to show each number like Clare did.

What did you notice as you were showing each number?

## Practice Problem

## Problem 1

How many cubes are there?

How do you see them?Show 14 with connecting cubes.