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: Construct a system of two linear equations where
$${(-2,3)}$$
is a solution to the first equation but not the second equation and where
$${(5,-2)}$$
is a solution to the system.


aligns: no