📚 First Grade Addition - Complete Notes & Formulas

🎯 1. Addition Facts - Sums Up to 10

Definition: Addition means combining two or more numbers to find the total.

Part 1 + Part 2 = Whole

Addend + Addend = Sum

Basic Addition Facts (0-10):

0 + 0 = 0 | 1 + 0 = 1 | 2 + 0 = 2
1 + 1 = 2 | 2 + 1 = 3 | 3 + 1 = 4
2 + 2 = 4 | 3 + 2 = 5 | 4 + 2 = 6
3 + 3 = 6 | 4 + 3 = 7 | 5 + 3 = 8
4 + 4 = 8 | 5 + 4 = 9 | 6 + 4 = 10
5 + 5 = 10

💡 Quick Tip: When adding 0 to any number, the answer is that same number! (5 + 0 = 5)

🔢 2. Ways to Make a Number - Addition Sentences

Different ways to make 5:

0 + 5 = 5
1 + 4 = 5
2 + 3 = 5
3 + 2 = 5
4 + 1 = 5
5 + 0 = 5

Different ways to make 10:

0 + 10 = 10 | 1 + 9 = 10 | 2 + 8 = 10
3 + 7 = 10 | 4 + 6 = 10 | 5 + 5 = 10
6 + 4 = 10 | 7 + 3 = 10 | 8 + 2 = 10
9 + 1 = 10 | 10 + 0 = 10

✍️ 3. Complete the Addition Sentence

? + 3 = 7 → Think: What number plus 3 equals 7?
Answer: 4 + 3 = 7

💡 Strategy: Use counting up or your fingers to find the missing number!

📖 4. Addition Word Problems - Sums Up to 10

Word Problem Format:
Look for: "How many in all?" | "How many altogether?" | "What is the total?"

Example: Tom has 3 apples. Mary gives him 4 more apples. How many apples does Tom have now?

3 + 4 = 7 apples

Steps to Solve:

Read the problem carefully
Find the two numbers (parts)
Write the addition sentence
Count or add to find the answer
Write the answer with a label (apples, toys, etc.)

🌟 5. Addition Facts - Sums Up to 18

Addition Facts (11-18):

5 + 6 = 11 | 6 + 6 = 12 | 7 + 6 = 13
6 + 7 = 13 | 7 + 7 = 14 | 8 + 7 = 15
8 + 8 = 16 | 9 + 8 = 17 | 9 + 9 = 18
10 + 5 = 15 | 10 + 6 = 16 | 10 + 7 = 17 | 10 + 8 = 18

➡️ 6. Addition Using Number Lines

Start at the first number → Count forward by the second number

Example: 7 + 5 = ?

1. Start at 7 on the number line

2. Make 5 hops forward (jump to 8, 9, 10, 11, 12)

3. You land on 12!

7 + 5 = 12

💡 Pro Tip: Always start with the BIGGER number and count forward the smaller number to make fewer hops!

📝 7. Addition Word Problems - Sums Up to 18

Example: There are 9 birds in a tree. 7 more birds fly to the tree. How many birds are in the tree now?

9 + 7 = 16 birds

⭐ 8. Addition Facts - Sums Up to 20

10 + 10 = 20
11 + 9 = 20 | 12 + 8 = 20 | 13 + 7 = 20
14 + 6 = 20 | 15 + 5 = 20 | 16 + 4 = 20
17 + 3 = 20 | 18 + 2 = 20 | 19 + 1 = 20

🔄 9. Related Addition Facts (Fact Families)

Commutative Property: The order of addends doesn't change the sum!

a + b = b + a

Fact Family for 3, 4, and 7:

3 + 4 = 7
4 + 3 = 7

These are related facts!

More Examples:

5 + 2 = 7 and 2 + 5 = 7
6 + 3 = 9 and 3 + 6 = 9
8 + 4 = 12 and 4 + 8 = 12

✅ 10. Addition Sentences: True or False?

How to Check:

Solve the addition problem
Compare your answer with the given answer
If they match = TRUE ✓
If they don't match = FALSE ✗

Examples:

5 + 3 = 8 → TRUE ✓
4 + 6 = 11 → FALSE ✗ (Should be 10)
7 + 2 = 9 → TRUE ✓
8 + 5 = 14 → FALSE ✗ (Should be 13)

➕ 11. Add One-Digit to Two-Digit (Without Regrouping)

Rule: When the ones place sum is less than 10, no regrouping needed!

Tens | Ones
2 | 3
+ | 4
____
2 | 7

23 + 4 = 27

More Examples:

31 + 5 = 36
42 + 3 = 45
51 + 6 = 57
60 + 8 = 68
74 + 2 = 76

Steps:

Keep the tens digit the same
Add the one-digit number to the ones place
Write the answer

🔁 12. Add One-Digit to Two-Digit (WITH Regrouping)

When to Regroup: When ones place adds up to 10 or more!

¹
Tens | Ones
2 | 8
+ | 5
____
3 | 3

28 + 5 = 33

(8 + 5 = 13, write 3 in ones, carry 1 to tens)

Step-by-Step Example: 37 + 6

1. Add ones: 7 + 6 = 13

2. Write 3 in ones place

3. Carry 1 to tens place

4. Add tens: 1 + 3 = 4

Answer: 43

More Practice:

25 + 7 = 32 (5+7=12, regroup!)
48 + 6 = 54 (8+6=14, regroup!)
59 + 8 = 67 (9+8=17, regroup!)
36 + 9 = 45 (6+9=15, regroup!)

🎓 Key Strategies for First Grade Addition

Strategy 1: Counting On

Start with the bigger number and count up!
Example: 8 + 3 → Start at 8, count "9, 10, 11" = 11

Strategy 2: Make 10

Break numbers to make 10 first, then add the rest!
Example: 8 + 5 → (8 + 2) + 3 = 10 + 3 = 13

Strategy 3: Doubles Facts

Same number + same number

1+1=2 | 2+2=4 | 3+3=6 | 4+4=8 | 5+5=10
6+6=12 | 7+7=14 | 8+8=16 | 9+9=18 | 10+10=20

Strategy 4: Doubles Plus One (Near Doubles)

If you know doubles, add one more!
Example: 6 + 7 → Think 6 + 6 = 12, plus 1 more = 13

Strategy 5: Adding Zero

Any number plus 0 equals that same number!

5 + 0 = 5 | 12 + 0 = 12 | 0 + 9 = 9

Strategy 6: Adding One

Adding 1 means counting forward by 1!

7 + 1 = 8 | 12 + 1 = 13 | 1 + 15 = 16

📊 Quick Reference Chart

Addition Vocabulary:

Addend: Numbers being added together
Sum: The answer in addition
Plus (+): The addition symbol
Equals (=): Shows the answer
Regroup: Make a ten from 10 ones
Total: Another word for sum

Remember: Practice makes perfect! The more you practice these addition facts, the faster you'll become! 🌟