Damages for breach by either party may be liquidated in the agreement but only at an amount which is reasonable in the light of the anticipated or actual harm caused by the breath, the difficulties of proof of loss and the inconvenience or nonfeasibility of otherwise obtaining an adequate remedy. A term fixing unreasonably large liquidation damages is void as a penalty.
No such board may enter into a contract of employment with a teacher for any period of time as to which the teacher is then under a contract of employment with another board.