To instill religious awareness in the students of Doña Trinidad High School, a public school in Bulacan, the Parent-Teacher's Association of the school contributed funds for the construction of a grotto and a chapel where ecumenical religious services and seminars are being held after school hours. The use of the school grounds for these purposes was questioned by a parent who does not belong to any religious group. As his complaint was not addressed by the school officials, he filed an administrative complaint against the principal before the DECS. Is the principal liable? Explain briefly. (5%)