1.OA.3
Apply properties of operations as strategies to add and subtract.3 Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)
| 1. | Add these three numbers: 4+2+3 | |
| 2. | Add these 3 numbers: 5+5+1 | |
| 3. | Add these 3 numbers: 6+4+5 | |
| 4. | 11 + 6 = 17: So what else is true? | |
| 5. | 11+6=17: So what else is true? | |
| 6. | 21+5=26: So what else is true? | |
| 7. | 15+12=27: So what else is true? |