Addition Strategies Within 20 | 1st Grade Math

Addition Strategies Within 20 - Grade 1 Math
Grade 1 Math  ›  Addition & Subtraction  ›  Lesson 9
Grade 1 Math - Addition and Subtraction

Addition Strategies Within 20

Learn useful addition strategies within 20 by counting on, starting with the larger addend, and making a ten. Choose a strategy that fits the numbers and makes addition easier.

This first grade addition lesson uses number lines, ten-frames, visual models, and decomposing numbers to help students solve addition facts within 20 with understanding and confidence.

Addition within 20 Count on Make a ten Addition strategies Grade 1 addition

๐ŸŽฏ What You Will Learn

Count on
Start with a number and count forward to add a small amount.
Start with the larger addend
Switch the addends when that makes the counting easier.
Make a ten
Break apart one addend so the other addend can reach 10.
Choose a strategy
Use the method that is clear and efficient for the numbers in the problem.
For parents & teachers — standards alignment: This lesson addresses the addition-strategy component of CCSS 1.OA.C.6 by developing addition within 20 through strategies such as counting on and making ten. It also supports CCSS 1.OA.C.5 by relating counting to addition and CCSS 1.OA.B.3 when students switch the order of addends as a strategy. Grade 1 students do not need to use formal property names here.

๐Ÿง  Key Vocabulary

addend — a number being added.
sum — the result of addition.
count on — start at a number and count forward to add.
make a ten — break apart an addend so another addend can reach 10.
decompose — break a number into smaller parts.
strategy — a useful way to solve a problem.

๐Ÿ› ️ Three Useful Addition Moves

๐Ÿ‘ฃ Count on

Start with the larger addend and count forward a small number of steps.

๐Ÿ”Ÿ Make a ten

Break apart one addend so the other addend can reach 10.

๐Ÿ”„ Switch the order

If it helps, put the larger addend first. The sum stays the same.

Scope note: This lesson concentrates on counting on, switching the order of addends, and making ten. Doubles and near-doubles are important too, but they receive their own focused MathLattice lesson later.

๐Ÿ‘ฃ Strategy 1: Count On

Counting on is useful when one addend is small. For 6 + 3, start at 6 and count forward three numbers: 7, 8, 9.

๐Ÿ”„ Strategy 2: Start with the Larger Addend

For 2 + 8, it is easier to think 8 + 2. Start at 8 and count on two numbers: 9, 10. The order of the addends can change without changing the sum.

Student-friendly idea: We do not need the formal name of this property yet. We only need to know that 2 + 8 and 8 + 2 have the same sum.

๐Ÿ”Ÿ Strategy 3: Make a Ten

Making 10 is especially helpful when an addend is close to 10. To solve 8 + 5, move 2 from the group of 5 to join the 8. That makes 10, with 3 left: 8 + 5 = 8 + 2 + 3 = 10 + 3 = 13.

Common mistake: When you move part of an addend to make 10, the total amount must stay the same. If 5 is split into 2 and 3, do not keep all 5 and add an extra 2.

๐ŸŒŸ 25 Worked Examples

✏️ Try each problem first. Then tap “Show solution” to compare strategies.
1Count on 2
Find 5 + 2.
✨ Show solution ๐Ÿ™ˆ Hide solution

Start at 5 and count on two numbers: 6, 7. Answer: 5 + 2 = 7.

2Count on 3
Find 6 + 3.
✨ Show solution ๐Ÿ™ˆ Hide solution

Start at 6 and count on three numbers: 7, 8, 9. Answer: 6 + 3 = 9.

3Start with the larger addend
Find 2 + 8.
✨ Show solution ๐Ÿ™ˆ Hide solution

It is easier to start at 8 and count on 2: 9, 10. The order can be switched without changing the sum. Answer: 2 + 8 = 10.

4Choose counting on
Find 7 + 2.
✨ Show solution ๐Ÿ™ˆ Hide solution

Because 2 is small, count on from 7: 8, 9. Answer: 7 + 2 = 9.

5Make a ten with 9
Find 9 + 4.
✨ Show solution ๐Ÿ™ˆ Hide solution

9 needs 1 more to make 10. Break 4 into 1 and 3. Then 9 + 1 = 10, and 10 + 3 = 13. Answer: 9 + 4 = 13.

6Make a ten with 8
Find 8 + 5.
✨ Show solution ๐Ÿ™ˆ Hide solution

8 needs 2 more to make 10. Break 5 into 2 and 3. Then 8 + 2 = 10, and 10 + 3 = 13. Answer: 8 + 5 = 13.

7Make a ten with 7
Find 7 + 5.
✨ Show solution ๐Ÿ™ˆ Hide solution

7 needs 3 more to make 10. Break 5 into 3 and 2. Then 7 + 3 = 10, and 10 + 2 = 12. Answer: 7 + 5 = 12.

8Make a ten with 6
Find 6 + 7.
✨ Show solution ๐Ÿ™ˆ Hide solution

6 needs 4 more to make 10. Break 7 into 4 and 3. Then 6 + 4 = 10, and 10 + 3 = 13. Answer: 6 + 7 = 13.

9Bridge through 10
Find 9 + 6.
✨ Show solution ๐Ÿ™ˆ Hide solution

9 needs 1 more to make 10. Break 6 into 1 and 5. Then 9 + 1 = 10, and 10 + 5 = 15. Answer: 9 + 6 = 15.

10Another bridge through 10
Find 8 + 7.
✨ Show solution ๐Ÿ™ˆ Hide solution

8 needs 2 more to make 10. Break 7 into 2 and 5. Then 8 + 2 = 10, and 10 + 5 = 15. Answer: 8 + 7 = 15.

11Switch, then make 10
Find 4 + 9.
✨ Show solution ๐Ÿ™ˆ Hide solution

Switch the order to think 9 + 4. Break 4 into 1 and 3. Then 9 + 1 + 3 = 10 + 3 = 13. Answer: 4 + 9 = 13.

12Switch, then count on or make 10
Find 3 + 8.
✨ Show solution ๐Ÿ™ˆ Hide solution

Start with 8. You can count on 3: 9, 10, 11. Answer: 3 + 8 = 11.

13Make 10 from 9 + 5
Find 5 + 9.
✨ Show solution ๐Ÿ™ˆ Hide solution

Switch the order: 9 + 5. Break 5 into 1 and 4. Then 9 + 1 + 4 = 10 + 4 = 14. Answer: 5 + 9 = 14.

14Decompose to make 10
Find 6 + 8.
✨ Show solution ๐Ÿ™ˆ Hide solution

Think 8 + 6. Eight needs 2 to make 10, so break 6 into 2 and 4. Then 8 + 2 + 4 = 10 + 4 = 14. Answer: 6 + 8 = 14.

15Use 10 as a friendly number
Find 7 + 8.
✨ Show solution ๐Ÿ™ˆ Hide solution

Think 8 + 7. Eight needs 2, so break 7 into 2 and 5. Then 8 + 2 + 5 = 10 + 5 = 15. Answer: 7 + 8 = 15.

16Add 9 and 8
Find 9 + 8.
✨ Show solution ๐Ÿ™ˆ Hide solution

9 needs 1 more to make 10. Break 8 into 1 and 7. Then 9 + 1 = 10, and 10 + 7 = 17. Answer: 9 + 8 = 17.

17Add 8 and 6
Find 8 + 6.
✨ Show solution ๐Ÿ™ˆ Hide solution

8 needs 2 more to make 10. Break 6 into 2 and 4. Then 8 + 2 = 10, and 10 + 4 = 14. Answer: 8 + 6 = 14.

18Add 7 and 9
Find 7 + 9.
✨ Show solution ๐Ÿ™ˆ Hide solution

Switch the order to 9 + 7. Break 7 into 1 and 6. Then 9 + 1 + 6 = 10 + 6 = 16. Answer: 7 + 9 = 16.

19Pick an efficient strategy
Which strategy is especially efficient for 6 + 2: count on or make a ten?
✨ Show solution ๐Ÿ™ˆ Hide solution

Count on is especially efficient because only two steps are needed: 7, 8. Answer: count on; 6 + 2 = 8.

20Pick a strategy for 9 + 5
Which strategy is especially useful for 9 + 5: count on or make a ten?
✨ Show solution ๐Ÿ™ˆ Hide solution

Make a ten is useful because 9 needs only 1 more to become 10. Break 5 into 1 and 4: 9 + 1 + 4 = 10 + 4 = 14. Answer: make a ten; 9 + 5 = 14.

21Explain the decomposition
To solve 8 + 5 by making 10, how should 5 be broken apart?
✨ Show solution ๐Ÿ™ˆ Hide solution

Eight needs 2 to make 10. Break 5 into 2 and 3. Answer: 5 = 2 + 3.

22Spot the mistake
A student writes 8 + 6 = 8 + 2 + 6 = 16. What went wrong?
✨ Show solution ๐Ÿ™ˆ Hide solution

The student added an extra 2 instead of taking that 2 from the 6, so the total changed. Split 6 into 2 and 4: 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14. Correct answer: 8 + 6 = 14.

23Compare two choices
For 6 + 3, which is simpler: count on 3 or break 3 apart to make 10?
✨ Show solution ๐Ÿ™ˆ Hide solution

Counting on 3 is simpler here: 7, 8, 9. Good mathematicians choose a strategy that fits the numbers. Answer: count on; 6 + 3 = 9.

24Switching the addends
Why can 3 + 9 be solved by thinking 9 + 3?
✨ Show solution ๐Ÿ™ˆ Hide solution

Changing the order of the addends does not change the sum. Starting with 9 makes counting on or making 10 easier. Answer: both sums equal 12.

25Challenge: make 10
Find 8 + 9 and show a make-10 strategy.
✨ Show solution ๐Ÿ™ˆ Hide solution

Eight needs 2 to make 10. Break 9 into 2 and 7. Then 8 + 2 + 7 = 10 + 7 = 17. Answer: 8 + 9 = 17.

๐ŸŽฎ Independent Practice — 30 Problems

  1. Find the sum: 4 + 2.
  2. Find the sum: 5 + 3.
  3. Find the sum: 7 + 2.
  4. Find the sum: 8 + 3.
  5. Find the sum: 9 + 2.
  6. Use a make-10 strategy: 9 + 4.
  7. Use a make-10 strategy: 8 + 5.
  8. Use a make-10 strategy: 7 + 5.
  9. Use a make-10 strategy: 6 + 7.
  10. Use a make-10 strategy: 9 + 6.
  11. Use a make-10 strategy: 8 + 7.
  12. Use a make-10 strategy: 7 + 8.
  13. Use a make-10 strategy: 9 + 8.
  14. Use a make-10 strategy: 6 + 9.
  15. Use a make-10 strategy: 5 + 8.
  16. Start with the larger addend to solve 2 + 9.
  17. Start with the larger addend to solve 3 + 8.
  18. Start with the larger addend to solve 4 + 9.
  19. Start with the larger addend to solve 2 + 7.
  20. Start with the larger addend to solve 3 + 9.
  21. Complete the make-10 step: 8 + 5 = 8 + 2 + □.
  22. Complete the make-10 step: 9 + 6 = 9 + 1 + □.
  23. Complete the make-10 step: 7 + 5 = 7 + 3 + □.
  24. Complete the make-10 step: 6 + 8 = 6 + 4 + □.
  25. True or false: 9 + 7 = 16.
  26. Which split helps solve 8 + 5 by making 10: 5 = 2 + 3 or 5 = 1 + 4?
  27. How many should be moved from the 4 in 9 + 4 to make 10 with 9?
  28. In 7 + 6, how many from the 6 are used to make 10 with 7?
  29. Explain in one sentence why switching 3 + 9 to 9 + 3 can help.
  30. Challenge: Find 8 + 9 using a make-10 strategy.

๐Ÿ† Lesson Test — 15 Questions

  1. Find the sum: 4 + 3.
  2. Find the sum: 7 + 3.
  3. Use a make-10 strategy to find 8 + 4.
  4. Use a make-10 strategy to find 9 + 3.
  5. Use a make-10 strategy to find 7 + 6.
  6. Find 8 + 9.
  7. Start with the larger addend to solve 2 + 8.
  8. Complete: 9 + 5 = 9 + 1 + □.
  9. Complete: 8 + 7 = 8 + 2 + □.
  10. To solve 7 + 5 by making 10, how can 5 be split?
  11. True or false: 8 + 5 = 13.
  12. Fix the mistake: 9 + 4 = 9 + 1 + 4 = 14.
  13. Which strategy is especially efficient for 7 + 1: count on or make a ten? Find the sum too.
  14. What strategy breaks apart an addend so another addend can reach 10 before adding the leftover part?
  15. Challenge: Find 6 + 9 and show a make-10 step.

๐Ÿ” Complete Answer Key

Answer-key note: Some strategy problems can be solved correctly in more than one way. The key below shows one clear Grade 1 method for each strategy item.
๐Ÿ”‘ Show practice answer key ๐Ÿ™ˆ Hide practice answer key

Practice Answers

1. 6
2. 8
3. 9
4. 11
5. 11
6. 9 + 4 = 9 + 1 + 3 = 10 + 3 = 13
7. 8 + 5 = 8 + 2 + 3 = 10 + 3 = 13
8. 7 + 5 = 7 + 3 + 2 = 10 + 2 = 12
9. 6 + 7 = 6 + 4 + 3 = 10 + 3 = 13
10. 9 + 6 = 9 + 1 + 5 = 10 + 5 = 15
11. 8 + 7 = 8 + 2 + 5 = 10 + 5 = 15
12. 7 + 8 = 7 + 3 + 5 = 10 + 5 = 15
13. 9 + 8 = 9 + 1 + 7 = 10 + 7 = 17
14. 6 + 9 = 9 + 6 = 9 + 1 + 5 = 10 + 5 = 15
15. 5 + 8 = 8 + 5 = 8 + 2 + 3 = 10 + 3 = 13
16. 2 + 9 = 9 + 2 = 11
17. 3 + 8 = 8 + 3 = 11
18. 4 + 9 = 9 + 4 = 13
19. 2 + 7 = 7 + 2 = 9
20. 3 + 9 = 9 + 3 = 12
21. 3
22. 5
23. 2
24. 4
25. True
26. 5 = 2 + 3
27. 1
28. 3
29. Starting with 9 leaves only 3 to count on (or makes it easier to make 10).
30. 8 + 9 = 8 + 2 + 7 = 10 + 7 = 17
๐Ÿ… Show test answer key ๐Ÿ™ˆ Hide test answer key

Test Answers

1. 7
2. 10
3. 8 + 4 = 8 + 2 + 2 = 10 + 2 = 12
4. 9 + 3 = 9 + 1 + 2 = 10 + 2 = 12
5. 7 + 6 = 7 + 3 + 3 = 10 + 3 = 13
6. 17
7. 2 + 8 = 8 + 2 = 10
8. 4
9. 5
10. 5 = 3 + 2
11. True
12. 9 + 4 = 9 + 1 + 3 = 13.
13. Count on; 7 + 1 = 8.
14. Make a ten.
15. 6 + 9 = 9 + 6 = 9 + 1 + 5 = 10 + 5 = 15.

๐Ÿ’ก Common Mistakes to Watch For

Counting both addends from 1 every time
This can work, but starting with one addend and counting on is often more efficient.
Adding extra counters when making 10
Break an addend apart; do not create new counters.
Forgetting the leftover part
After making 10, add the part that remains.
Using the same strategy every time
A good strategy depends on the numbers. Counting on may be easier for +1, +2, or +3; making 10 may be easier near 10.
For parents & teachers — Texas connection: TEKS 1.3(D) expects students to apply basic fact strategies to add and subtract within 20, including making 10 and decomposing a number leading to a 10. This lesson develops the addition side of that expectation and also supports TEKS 1.3(E) by asking students to explain and compare strategies. Subtraction strategies are addressed in the next MathLattice lesson.

๐Ÿ”— Related Lessons

Lesson 8 — Number Bonds & Ways to Make 10
Review the partners of 10 before using make-10 addition strategies. Lesson 6 — Understanding Addition Within 10
Review what addition means with counters, pictures, and ten-frames.

๐Ÿ–จ️ Printable Companion

A free Addition Strategies Within 20 Practice Pack will be connected here as the MathLattice printable library grows. It will include count-on practice, make-10 models, ten-frames, strategy choice, error analysis, mixed practice, and an answer key.

← Lesson 8: Number Bonds & Ways to Make 10 Grade 1 Math Hub Next: Subtraction Strategies Within 20 →

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