Amends the Employment of Teachers Article of the School Code. In a provision requiring a school board, before setting a hearing on charges stemming from causes that are considered remediable, to give a teacher reasonable warning, in writing, stating specifically the causes that, if not removed, may result in charges, allows a teacher to grieve the issuance of such warning pursuant to the applicable collective bargaining agreement to determine whether the board had just cause in issuing the warning. Requires the written warning to narrowly specify the nature of the alleged misconduct that needs to be remedied. Provides that under no circumstances may the written warning remain effective for longer than 4 years from the date of the issuance of the written warning. Requires the school district to use reasonable efforts to remove the written warning from the teacher's personnel file after the 4 years have elapsed or sooner if agreed to through the exclusive bargaining representative, with an exception. Effective immediately.