Final answer:
According to the Supreme Court, the reading of a nondenominational prayer at the start of the school day violates the Establishment Clause of the First Amendment.
Step-by-step explanation:
According to the Supreme Court case Engel v. Vitale in 1962, the reading of a nondenominational prayer at the start of the school day violates the Establishment Clause of the First Amendment. The Court ruled that by providing the prayer, the state of New York officially approved religion, thereby establishing a religion in violation of the Establishment Clause. This decision set a clear boundary between government and the endorsement of religious practices in public institutions, including public schools.