105 ILCS 5/22-5
No State, county, township, or district school officer or teacher shall be interested in the sale, proceeds or profits of any book, apparatus or furniture used or to be used in any school with which such officer or teacher may be connected, except when the interest of the teacher is based upon authorship or development of instructional materials listed with the State Board of Education in compliance with the provisions of Article 28 of this Act and adopted for use by a school board subject to Section 10-20.8 of this Act. Each teacher having an interest in instructional materials shall file an annual statement so certifying with the secretary of the board of the school district which employs him. Any such officer or teacher who violates the provisions of this Section shall be guilty of a Class A misdemeanor.
105 ILCS 5/22-5