(a) Each teacher in a public school of this State shall have a duty-free lunch period each regularly scheduled school day.
(b) This duty-free period shall be for at least 30 minutes, unless the students have a regular lunch period of less than 30 minutes in which case the duty- free period shall be the same as the regular lunch period.
(c) Each county board may employ teacher aides to carry out the purposes of this section.