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.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.
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).
