Lesson 1 Add and Subtract Within 10

- Let’s add and subtract within 20.

Warm-up What Do You Know About …?

What do you know about math?

Activity 1 Check It Off: Add or Subtract within 10

Pick 2 cards and find the value of the sum or difference.
Check off the number you found and write the expression.
The person who checks off the most numbers wins.

	Found it!	Expression
0
1
2
3
4
5
6
7
8
9
10

Activity 2 What’s the Value?

Problem 1

Match each expression to the value of the sum or difference.

$5 + 3$
$3 - 1$
$10 - 1$
$4 + 5$
$6 + 3$
$6 - 5$
$1 + 6$
$9 - 5$
$8 - 5$
$3 + 6$

$9$
$3$
$8$
$7$
$1$
$4$
$2$

Problem 2

Circle all the addition expressions that have a value of 20.

addition table.

Problem 3

What patterns do you see in the numbers in the expressions that have a value of 20?

Practice Problem

Problem 1

Find the value of each expression.

$9 - 2$
$5 + 3$
$2 + 8$
$7 - 4$
$10 - 3$
$1 + 6$