What is the constitutional provision concerning the teaching of religion in the elementary and high schools in the Philippines?

Under Section 3(3), Article XIV of the Constitution, at the option expressed in writing by the parents or guardians, religion shall be allowed to be taught to their children or wards in public elementary and high schools within the regular class hours by instructors designated or approved by the religious authorities of the religion to which the children or wards belong, without additional cost to the Government. (Bar 1999)