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Development of Mean Raw Calculation Ability Scores (Correctly Solved Items per Minute) for Each Calculation Performance Group From T1 (End of Grade 1) to T4 (Middle of Grade 3)
Note: Black line is the calculation score ≥ 15th percentile at all time points; long dashed line is the calculation score < 15th percentile at one or two time points; short dashed line is the calculation score < 15th percentile at three or four time points. Error bars represent standard deviations of the mean.
