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 = ?.
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.
