standard_description: Fluently add and subtract within 20 using mental strategies. (See standard 1.OA.6 for a list of mental strategies.) By end of Grade 2, know from memory all sums of two one-digit numbers.
problem_activity: Identify the strategy that the student below used to find the measure of
$${BA}$$
. Then, describe a different method for finding this value, describing how you know that the two triangles are dilations of one another.
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aligns: no