Addition
Add within 20 fluently — count on, make ten, and master the doubles.
1 Addition means joining
When groups join together, we add. The numbers being added are addends and the result is the sum.
Example: 8 apples + 5 apples = 13 apples. The plus sign (+) means “join”.
8 + 5 = 13. Eight things join five things to make thirteen.
2 Strategy 1: count on
Start at the bigger number and count up. For 8 + 5, hold 8 in your head, then count: 9, 10, 11, 12, 13.
9 + 4: start at 9, count on 4 → 10, 11, 12, 13.
3 Strategy 2: make ten
Ten is a friendly number. Break the smaller addend so one part completes the ten: 8 + 5 = 8 + 2 + 3 = 10 + 3.
7 + 6 = 7 + 3 + 3 = 10 + 3 = 13.
4 Strategy 3: doubles and near-doubles
Doubles (6 + 6) are worth memorizing. A near-double is one more: 6 + 7 = (6 + 6) + 1.
6 + 6 = 12.
6 + 7 is one more than 6 + 6, so 12 + 1 = 13.
5 Common mistakes
Two habits that slow counters down — replace them with count-on.
Wrong: for 8 + 5, counting 1, 2, 3, … all the way to 13. Right: start at the bigger number: 8 … 9, 10, 11, 12, 13. Faster and fewer slips.
Wrong: answering 8 + 5 with 31. Right: say “thirteen” aloud while you write 13. Thirteen is 1 ten and 3 ones.
6 Quick checks
Try these yourself, then reveal the answer.
7 Key points and vocabulary
| Word | What it means |
|---|---|
| Addend | A number being added. |
| Sum | The result of adding. |
| Count on | Starting at the bigger number and counting up. |
| Make ten | Breaking an addend to complete a ten first. |
| Doubles | An addition fact like 7 + 7 with equal addends. |
Remember
- Count on from the bigger number — never recount from 1.
- Make ten whenever a sum crosses 10.
- Memorize the doubles; near-doubles are one more.
- Say the sum aloud as you write it so digits never flip.