## Engage NY Eureka Math 1st Grade Module 1 Lesson 21 Answer Key

### Eureka Math Grade 1 Module 1 Lesson 21 Problem Set Answer Key

Add the numbers on the pairs of cards. Write the number sentences. Color doubles red. Color doubles plus 1 blue.

Question 1.

Question 2.

Question 3.

Question 4.

Solve. Use your doubles to help. Draw and write the double that helped.

Question 5.

Given the numbers are 5 and 4
To find the missing number
we get 9

Question 6.

Given the numbers are 3 and 4
To find the missing number
we get 7

Question 7.
Solve the doubles and the doubles plus 1 number sentences.

Question 8.
Show how this strategy can help you solve 5 + 6 =

Given the numbers are 5 and 6
To find the missing number
we get 11

Question 9.
Write a set of 4 related addition facts for the number sentences of Problem 7(d).
8+4+4
4+5=9
9=4+5

### Eureka Math Grade 1 Module 1 Lesson 21 Exit Ticket Answer Key

Write the double and double plus 1 number sentence for each 5-group card.

### Eureka Math Grade 1 Module 1 Lesson 21 Homework Answer Key

Question 1.
Draw the 5-group card to show a double. Write the number sentence to match the cards.
a.
Answer:The double  fact that hlped to solve the euqation is
4+4=8
For which the double+1 fact is 4+5=9

b.
Answer:The double  fact that hlped to solve the euqation is
3+3=6
For which the double+1 fact is 3+4=7

c.
Answer:The double  fact that hlped to solve the euqation is
5+5=10
For which the double+1 fact is 5+6=11

Question 2.
Fill in the 5-group cards in order from least to greatest, double the number, and write the number sentences.
a.

b.

c.

d.

e.

Question 3.
Solve the number sentences.
a. 3 + 3 = __

Given : two numbers are 3 and 3
By adding 3 with 3 we get 6
3 + 3 = 6

b. 5 + __ = 10

Given : two numbers are 5 and 10
by subracting 5 from 10 we get 5
10-5=5
so the issing number is 5
5 + 5 = 10

c. 1 + __ = 2

Given : two numbers are 1 and 2
by subracting 1 from 2 we get 1
2-1=1
so the issing number is 1
1+1=2

d. 4 = __ + 2

Given : two numbers are 4 and 2
by subracting 2 from 4 we get 2
4-2=2
so the issing number is 2
4 = 2 + 2

e. 8 = 4 + __

Given : two numbers are 4 and 8
by subracting 4 from 8 we get4
8-4=4
so the issing number is 5
8 = 4 + 4

Question 4.
Match the top cards to the bottom cards to show doubles plus 1.
a.

b.

c.

d.

Question 5.
Solve the number sentences. Write the double fact that helped you solve the double plus 1.
a.
Answer: The double +1 fact that hlped to solve the euqation is
2+3=5
For which the double fact is 2+2=4

b.
Answer:The double +1 fact that hlped to solve the euqation is
3+4=7
For which the double fact is 3+3=6

c.
Answer:The double +1 fact that hlped to solve the euqation is
4+5=9
For which the double fact is 4+4=8