Is teaching the Bible in public school unconstitutional?
It is not unconstitutional to teach about the Bible in public schools. This extends to all religions and religious texts. The education must be done in a secular manner, not endorsing or promoting any one belief.
It is unconstitutional for a public school to lead or advance the practice or belief of religions. It is also unconstitutional for a public school to lead prayers of any kind. The Equal Access Act of 1984 allows the establishment of student-led and student-initiated religious clubs in schools, but activities cannot be government or school-sponsored.
A 1969 Supreme Court case found that a school cannot restrict a student's speech or expression so long as it does not "materially and substantially interfere" with the operation of the school. The case specifically concerned the wearing of armbands in protest of the Vietnam War but has also protected student-practiced prayer (such as before meals or other personal practices).