105 ILCS 5/24-3: Attendance at teachers' institute.

The days in any school year spent by a teacher or educational support personnel during the term time spent in attendance upon a teachers' institute or equivalent professional educational experiences held under the direction of the county superintendent of schools shall be considered time expended in the service of the district and no deduction of wages shall be made for such attendance. The board may make a pro-rata deduction from the salary of any teacher or educational support personnel who fail or refuse to attend such institute, unless, in the case of educational support personnel, they are exempt from attending. The boards shall close the schools for county institute.