Final answer:
The best time to sample whether a child has mastered classroom scripts is at the beginning of the school year.
Step-by-step explanation:
The best time to sample whether a child has mastered classroom scripts is (a) at the beginning of the school year. This is because at the beginning of the school year, students are introduced to the classroom routines, procedures, and expectations.
It allows for a baseline assessment of the child's understanding and progress throughout the year. Sampling midway or at the end of the school year may not reflect a true measure of mastery, as the child may have already learned and adapted to the scripts by that time.