Kansas Academic Standards
KS.1.OA. Operations and Algebraic Thinking
Understand and apply properties of operations and the relationship between addition and subtraction.
1.OA.3. Apply (not necessary to name) properties of operations as strategies to add and subtract. Examples: 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.) To add 0 to any number, the answer is that number 7+0=7 (Additive identity property of 0.) Students need not use formal terms for these properties.
1.OA.4. example, subtract 10−8 by finding the number that makes 10 when added to 8.
Add and subtract within 20.
1.OA.5. Relate counting to addition and subtraction (e.g. by counting on 2 to add 2, counting back 1 to subtract 1).
1.OA.6. Add and subtract within 20, demonstrating fluency (efficiently, accurately, and flexibly) for addition and subtraction within 10. Use mental strategies such as counting on; making ten (e.g. 8+6=8+2+4=10+4=14); decomposing a number leading to a ten (e.g. 13−4=13−3−1=10−1=9); using the relationship between addition and subtraction (e.g. knowing that 8+4=12, one knows 12−8=4); and creating equivalent but easier or known sums (e.g. adding 6+7 by creating the known equivalent 6+6+1=12+1=13).