Final answer:
The school banned purses with Confederate flags due to their potential to disrupt school activities, which was upheld by the court, aligning with past decisions on the balance between free speech and educational order.
Step-by-step explanation:
The school banned the purses because they displayed large images of Confederate flags, which were deemed to violate the school's dress code by representing inappropriate symbolism and potentially discriminatory messages based on race. This stance was taken seriously because the imagery could materially and substantially disrupt school activities, as suggested by past legal precedence.
For instance, in a notable Supreme Court case, a school's prohibition of armbands was challenged, and it was declared that symbolic protest in schools is protected by the First Amendment unless it causes actual disruption. In the case of the Confederate flag purses, the court upheld the school district's decision, agreeing that such symbols could indeed lead to substantial interference within the educational environment.