2.OA.2:
Operations And Algebraic Thinking
Add And Subtract Within 20.
Fluently add and subtract within 20 using mental strategies.2 By end of Grade 2, know from memory all sums of two one-digit numbers.
2.NBT.5:
Number And Operations In Base Ten
Use Place Value Understanding And Properties Of Operations To Add And Subtract.
Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
2.NBT.9:
Number And Operations In Base Ten
Use Place Value Understanding And Properties Of Operations To Add And Subtract.
Explain why addition and subtraction strategies work, using place value and the properties of operations.3
1.OA.3:
Operations And Algebraic Thinking
Understand And Apply Properties Of Operations And The Relationship Between Addition And Subtraction.
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.OA.4:
Operations And Algebraic Thinking
Understand And Apply Properties Of Operations And The Relationship Between Addition And Subtraction.
Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
1.OA.5:
Operations And Algebraic Thinking
Add And Subtract Within 20.
Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
1.OA.6:
Operations And Algebraic Thinking
Add And Subtract Within 20.
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use 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).
1.OA.8:
Operations And Algebraic Thinking
Work With Addition And Subtraction Equations.
Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = ? - 3, 6 + 6 = ?.
