1.OA.C

Add and subtract within 20.

1.OA.C.5Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).1.OA.C.6Add 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).
Khan Academy Resources
Subtract within 20 visuallyAdd & subtract within 20Add within 20 visuallyAdding within 20 using place value blocksAdding within 20 using ten frames
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