As used in this subchapter—

(1) The term "secondary school" means a public school which provides secondary education as determined by State law.

(2) The term "sponsorship" includes the act of promoting, leading, or participating in a meeting. The assignment of a teacher, administrator, or other school employee to a meeting for custodial purposes does not constitute sponsorship of the meeting.

(3) The term "meeting" includes those activities of student groups which are permitted under a school's limited open forum and are not directly related to the school curriculum.

(4) The term "noninstructional time" means time set aside by the school before actual classroom instruction begins or after actual classroom instruction ends.