🔢Math Standard
Adding Three Numbers Worksheet (Within 20)
Add three numbers within 20 by finding a friendly pair first — a ten or a double.
1st Grade 10 min
✓ Answer key
1st Grade · Math
1st Grade Addition Worksheets
Reviewed by ClassReady Editorial Team Last updated August 2026
Before this skill
- Addition within 20
- Number pairs that make 10
- Counting to 10
- Counting on from a number
- Counting and number order to 20
Common mistakes to watch for
- Adding left to right and losing track
- Missing an easy pair (a ten or a double)
- Counting on the starting number itself
- Recounting both numbers from one every time
- Counting the starting number instead of counting on from it
Take the full lesson
Learn addition step by step with worked examples and practice exercises — no PDF required.
Filter:
🔢Math Easy
Addition Facts to 10 Worksheet
Practice addition facts with sums up to 10, using a number line to count on.
1st Grade 10 min
✓ Answer key
🔢Math Standard
Addition Within 20 Worksheet
Practice addition facts with sums up to 20, with a number line to count on from the larger number.
1st Grade 12 min
✓ Answer key
🔢Math Standard
Christmas Addition Word Problems (Within 20)
Solve Christmas addition word problems about ornaments, gifts, and cookies, with sums up to 20.
1st Grade 12 min
✓ Answer key
🔢Math Standard
Doubles and Doubles Plus One Worksheet
Use doubles you know to solve near-doubles: a doubles-plus-one fact is just the double and one more.
1st Grade 10 min
✓ Answer key
🔢Math Easy
Easter Addition Worksheet
Add the Easter egg sets and bunny baskets to find each total within 20.
1st Grade 10 min
✓ Answer key
🔢Math Standard
Make a Ten to Add Worksheet
Add within 20 by making a ten first: take from one number to fill the other up to 10, then add the rest.
1st Grade 10 min
✓ Answer key
🔢Math Standard
Missing Addends Worksheet
Find the missing addend that makes each addition sentence true.
1st Grade 10 min
✓ Answer key
🔢Math Easy
Spring Addition Worksheet
Add the spring sets — flowers, eggs, and bees — to find each total within 20.
1st Grade 10 min
✓ Answer key
🔢Math Easy
St. Patrick's Day Addition Worksheet
Add the shamrock and gold coin sets to find each total within 20.
1st Grade 10 min
✓ Answer key
🔢Math Standard
True or False Equations Worksheet
Decide if each equation is true or false, then fill in a number to make equations true.
1st Grade 12 min
✓ Answer key
🔢Math Standard
Valentine's Day Addition Word Problems (Within 20)
Solve Valentine's Day addition word problems about hearts, cards, and candy, with sums up to 20.
1st Grade 12 min
✓ Answer key
Suggested Practice Sequence
- 1 Addition Facts to 10 Worksheet easy
- 2 Easter Addition Worksheet easy
- 3 Spring Addition Worksheet easy
- 4 St. Patrick's Day Addition Worksheet easy
- 5 Adding Three Numbers Worksheet (Within 20) standard
- 6 Addition Within 20 Worksheet standard
- 7 Christmas Addition Word Problems (Within 20) standard
- 8 Doubles and Doubles Plus One Worksheet standard
- 9 Make a Ten to Add Worksheet standard
- 10 Missing Addends Worksheet standard
- 11 True or False Equations Worksheet standard
- 12 Valentine's Day Addition Word Problems (Within 20) standard
Related Skills
Frequently Asked Questions
What do 1st Grade students practice with addition?
Students will add three whole numbers with a total within 20, looking for a make-a-ten or doubles pair first.
Are these worksheets free and printable?
Yes — every worksheet is a free, printable PDF with an answer key. No sign-up required.