K–2 Math · Lesson 4 of 8
Lesson 4: Addition
Addition means putting groups together to find the total. When you add 2 apples and 3 apples, you get 5 apples!
Key Concepts
The Plus Sign
The + sign means we are putting two groups together. 3 + 4 means three things AND four things put together. The answer is called the sum.
Order Does Not Matter
3 + 5 is the same as 5 + 3. Both equal 8! In addition, you can flip the numbers and get the same answer. This is called the commutative property — a fancy way of saying order doesn't matter!
Adding with a Number Line
A number line helps us add. Start at the first number, then jump forward the second number of spaces. Where you land is the answer!
🆕 Activity: Addition Machine
Use the sliders to pick two numbers and add them together!
✅ Check Your Understanding
1. What does the + sign mean?
2. What is 4 + 3?
3. Does 2 + 5 equal the same as 5 + 2?