To examine teachers by examinations supplemental to any other examinations and to employ teachers and fix the amount of their salaries subject to limitations set forth in this Act. Provided, that in fixing salaries of certificated employees school boards shall make no discrimination on account of sex; provided, further, that sabbatical leaves, with full or partial salary, may be granted in accordance with the rules of the board.
105 ILCS 5/10-21.1