The OP requires the following information, for the benefit of non-USA Dopers:
(a) It’s a tradition in many school districts, a “rule” in many schools, but in just as many others it’s not required and not done; the latter may for all I know now represent a numerical majority of the pupils enrolled. Some school districts “require” it, but it’s really up to the schools principals to enforce it.
(b) School organization and management in the USA is a local-community jurisdiction, under school districts ruled by school boards that are mostly elected, often in elections separate from those for the general local governments. The school district may not necessarily coincide geopolitically with the city, town or county and is usually funded by the real-property tax in the locality. The Statewide and Federal education departments deal with setting common standards, protecting the rights of students and employees, and providing supplemental funding.
© It has been determined by the US Supreme Court, as far back as 1943, that no student may be forced to make the Pledge of Allegiance against their beliefs/wishes
(d) Some so-called “traditional values conservatives” believe that a return to strict observance of the Pledge, and maybe also a pre-class prayer, would be the solution to all problems of degeneracy of the American collective character. Conveniently forgetting that their detested 1960s hippies and “liberals” grew up saying the Pledge and the prayers (Hmmm… waittaminute…)
(e) The rite consists of standing facing the flag, placing hand-on-heart, and reciting “I Pledge allegiance to the Flag of the United States of America and to the Republic for which it stands; one nation (under God), indivisible, with liberty and justice for all.” (The “under God” bit added in a fit of self-righteousness in the 1950)