Sec. 21. (a) This section and section 22 of this chapter apply to the suspension of a teacher without pay.
(b) A teacher may be suspended from duty without pay only for the following reasons:
(1) Immorality.
(2) Insubordination, which means the willful refusal to obey the state school laws or reasonable rules prescribed for the government of the school corporation.
(3) Neglect of duty.
(4) Substantial inability to perform teaching duties.
(5) Good and just cause.