2.OA.B.2
Fluently add and subtract within 20 using mental strategies. By end of grade 2, know from memory all sums of two single-digit numbers and related differences. For example, the sum 6 + 5 = 11 has related differences of 11 – 5 = 6 and 11 – 6 = 5.
Khan Academy ResourcesAdd within 20Subtract within 20Subtract within 20 visuallyAdd & subtract within 20Add within 20 visuallyAdd and subtract within 20 word problemsSubtract within 20 using ten framesSubtract within 20 using a number lineAdding 7 + 6Addition and subtraction word problems: superheroesSubtract within 20 using place value blocksAdding 8 + 7Subtracting 14 - 6Adding within 20 using place value blocksAddition and subtraction word problems: gorillasAdding within 20 using ten frames

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