Section D: Practice Problems Subtract Within 20

Section Summary

Details

We used different methods to subtract within 20.

We used take away methods.

$15 - 8$

Ten frame. 7 counters not crossed out. 3 counters crossed out.

We used a ten to take away 8.

Ten frame, full. 8 counters crossed out. 2 counters not crossed out.

We used counting on methods.

$15 - 8$
8…9, 10, 11, 12, 13, 14, 15

Use ten to help count on.
$8 + 2 = 10$
$10 + 5 = 15$
$2 + 5 = 7$

Problem 1 (Lesson 22)

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

$12 - 3 =$
$19 - 5 =$

Problem 2 (Lesson 23)

Find the value of each difference.
Show your thinking using drawings, numbers, or words.

$16 - 10$
$16 - 9$

Problem 3 (Lesson 24)

Find the value of each difference.
Use the 10-frames if they help.

$13 - 9$
$14 - 6$

Problem 4 (Lesson 25)

Find the number that makes each equation true.

$15 - 11 =$
$14 - 5 =$

Problem 5 (Lesson 26)

There are some children skating on the pond.
Then 8 more children come to join them.
Now there are 14 children skating on the pond.
How many children were skating on the pond before more joined?
Show your thinking using drawings, numbers, or words.

Problem 6 (Exploration)

Mai was playing Number Card Subtraction.
She started with a teen number.
Then she drew a card and subtracted.
Mai’s answer was the same as the number she subtracted.
What could Mai’s teen number and card have been?

Problem 7 (Exploration)

Find the value of the expression in as many ways as you can.

$16 - 9$

What is your favorite way?