Answer: the establishment clause of the First Amendment which calls for the separation of church and state
Explanation:
Based on the information, the aspect of the Constitution that John Doe is most likely arguing that the school district is violating is the establishment clause of the First Amendment which calls for the separation of church and state.
According to the First Amendment's Establishment Clause, the government is prohibited from making a law that respects the establishment of a religion. Also, the clause forbids the government from favoring one religion over another religion.