The correct answer would include such ideas as the following: The United States Constitution in Article I, Section 8 identifies the legislative power of Congress. Education is not mentioned in that section. In the Bill of Rights, Amendment X indicates that those powers not given to the federal government and not denied to the states are powers reserved for the states. Hence, states, not the federal government, have the power to decide what will be taught in the public schools of the United States.
Note that in answering the above question teachers might choose to have students have in hand copies of the U.S. Constitution.