Final answer:
Scout's teacher in 'To Kill a Mockingbird' is indeed upset that Scout can already read and write because it challenges the structured educational approach of the time.
Step-by-step explanation:
The statement that Scout's first grade teacher is upset because Scout can read and write is indeed true. In the novel To Kill a Mockingbird, Scout's ability to read and write before her formal education begins is frowned upon by her teacher, Miss Caroline Fisher, as it deviates from the standard educational practices of the time. The teacher believes in a structured approach to learning where she is the one imparting knowledge to the students, and Scout having this knowledge beforehand undermines that structure. Moreover, the ability to read and write was considered a part of the structured curriculum, and learning it outside of this framework was unexpected and even unwelcome by some educational professionals of that era.