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Fish Tank Subtraction: Use an Addition Fact worksheet preview

Worksheet

Fish Tank Subtraction: Use an Addition Fact

Grade 1 practice solving subtraction within 20 by finding the unknown addend, with fish tank stories, fact matching, and answer checks.

Grade 1MathInteractive · Printable

Aligned to1.OA.B.4

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What’s included

  • Single worksheet
  • Auto-graded online
  • 1 Common Core standard
  • Printable answer key
  • 12 questions
  • Classroom-ready

Details

Format
Interactive · Printable
Grade
Grade 1
Subject
Math
Question types
Fill in the blank, Multiple choice, Matching, Sorting, Short answer

About this worksheet

What students practice

  • Students solve subtraction within 20 by finding the missing addend in a related addition fact.
  • Students choose the addition fact that helps solve a subtraction problem.
  • Students use addition to check whether a subtraction answer is correct.

How to use

Model the first problem with counters: start with the part you know and count up to the whole. Then have students solve the rest and explain one answer to a partner.

Curriculum

Common Core standard covered

1.OA.B.4

Treat subtraction as finding an unknown addend.

Preview

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Name Date

Fish Tank Subtraction: Use an Addition Fact

Solve each subtraction by finding the missing addend.

Find the Missing Number

Use an addition fact to solve each subtraction.

1.
There are 12 fish in the tank. 8 fish are orange. The rest are blue. How many fish are blue?

8 +   = 12, so 12 − 8 =   blue fish

2.

To find 15 − 9, think 9 +   = 15.

3.

To find 11 − 7, think 7 +   = 11.

4.

17 − 8 =   because 8 +   = 17.

5.
Think of an addition fact to help you.

13 − 6 =  

Fish Tank Stories

Read each story. Think addition to solve it.

6.
There are 14 snails in the tank. 5 snails are on the glass. The rest are on the rocks. How many snails are on the rocks?

  snails are on the rocks.

7.
Ella needs 10 plants for the class fish tank. She has 3 plants. Which addition fact helps her find how many more plants she needs?
  • A. 3 + 10 = 13
  • B. 3 + 7 = 10
  • C. 10 + 7 = 17
8.
Which subtraction can you solve with 6 + 9 = 15?
  • A. 15 − 6
  • B. 15 − 5
  • C. 9 − 6
  • D. 16 − 9
9.
Match each subtraction to the addition fact that helps you solve it.
  1. 18 − 9
  2. 14 − 6
  3. 12 − 5
  4. 16 − 7
  1. A. 5 + 7 = 12
  2. B. 7 + 9 = 16
  3. C. 9 + 9 = 18
  4. D. 6 + 8 = 14
10.
There are 19 guppies in the tank. Some guppies swim behind the castle. Now you can see 10 guppies. How many guppies are behind the castle?

  guppies are behind the castle.

Check the Answers

Use addition to check each subtraction.

11.
Add to check each answer. Sort each subtraction as correct or not correct.
13 − 4 = 911 − 3 = 720 − 10 = 1016 − 8 = 915 − 7 = 8
CorrectNot correct
12.
Leo says, "To find 14 − 8, I think 8 + 6 = 14." Is Leo right? Tell how you know and write the answer to 14 − 8.

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