Addition is gathering things and counting how many there are in all.
If a plate has 3 apples and you put 2 more on, you can count on four, five, and reach 5 without starting over.
We write that joining with the plus sign, as in 3 + 2 = 5.
Move the apple and banana sliders and step right on the number line: 3 + 2 and 2 + 3 are both 5.
What is Combining?
🤲 Combining = Putting Together
①2 apples in left hand, 3 apples in right
②Put hands together? → 5 apples!
③This is "addition"
④The symbol for combining is +
Let's Combine Fruits
3
2
3 + 2 = 5 and 2 + 3 = 5. Order does not change the sum
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Visualizing addition by combining two kinds of fruits
💡 Understanding Addition
①Combine apples and bananas
②Counting in order gives the total
③3 + 2 = 5 → "3 plus 2 is 5"
④Try changing the slider!
⑤Adding 0 leaves the count the same. Slide a number to 0 to see it
Adding on a Number Line
4
3
4 + 3 = 7 and 3 + 4 = 7. Order does not change the sum
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Adding by moving right on a number line
➡️ Adding on a Number Line
①The red dot is the starting number
②The dashed arc moves by the amount added
③The green dot is the answer!
④Adding moves right on the number line
Summary
Addition Symbol
Apple + Banana = Total
Plus (+) means combining two numbers
Adding 0
Any number + 0 = same number
Adding 0 keeps the same value (nothing added)
Switching Order
3 + 2 = 2 + 3 = 5
Order does not change the answer!
🎯 Remember!
①Addition is "combining"
②+ means "plus"
③Move right on a number line
④Adding 0 keeps it the same
⑤Order does not change the result!
Examples and Unit Test
Example 1
A plate has 3 apples. If you add 2 more apples, how many apples are there in all?
1
There are 3 apples to start.
2
Count on 2 from 3: 4, 5. So 3 + 2 = 5.
▸ 5 apples
Adding means gathering two numbers and counting them together.
Example 2
Alex has 6 candies and Sam has 3 candies. How many candies do they have altogether?
1
Add the two numbers: 6 + 3.
2
Count on 3 from 6: 7, 8, 9.
▸ 9 candies
6 + 3 equals 3 + 6. Changing the order does not change the sum.