# Section B: Practice Problems Add and Subtract Using Ten as a Unit

## Section Summary

Details

We learned that 10 ones make a ten.

We learned that all teen numbers can be represented as a ten and some ones.

We used that understanding to find missing numbers in addition and subtraction equations with teen numbers.

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We solved a new type of story problem where we don’t know how many to subtract. We used different equations to match the story.

There are 17 students in the classroom.
Some students go home.
Then there are 4 students in the classroom.
How many students went home?

## Problem 1 (Lesson 8)

1. How many cubes are there?
How do you see them?

2. Show 14 with connecting cubes.

## Problem 2 (Lesson 9)

Find the number that makes each equation true.
Show your thinking using drawings, numbers, or words.

## Problem 3 (Lesson 10)

1. Find the number that makes each equation true.

2. How are the 2 equations the same? How are they different?

## Problem 4 (Lesson 11)

Find the number that makes each equation true.

## Problem 5 (Lesson 12)

Find the number that makes each equation true.

## Problem 6 (Lesson 13)

There are 12 kids playing soccer.
Then 4 more come to play with them.
How many kids are playing soccer now?
Show your thinking using drawings, numbers, or words.

Equation:

## Problem 7 (Exploration)

Jada has 17 cards on her desk.
She gives Han 4 cards.
Now Han and Jada have the same number of cards.
How many cards were on Han’s desk to start?
Show your thinking using drawings, numbers, or words.

## Problem 8 (Exploration)

Jada has 14 cards on her desk.
Han has 15 cards on his desk.

1. How many cards does Jada have on her desk now?
Show your thinking using drawings, numbers, or words.

2. How many cards does Han have on his desk now?
Show your thinking using drawings, numbers, or words.

## Problem 9 (Exploration)

number

name

sixteen

seventeen

eighteen

nineteen

What do you notice about the numbers and names in the table?