The board of education of any school district may enter into a supplemental contract of employment with any employee of the district. As used in this section “supplemental contract” means a contract for services other than those services covered in the principal or primary contract of employment of such employee, and shall include but not be limited to such services as coaching, supervising, directing and assisting extra curricular activities, chaperoning, ticket taking, lunch room supervision and other similar and related activities. The provisions of article 22 of chapter 72 of [the] Kansas Statutes Annotated which relate to the continuation of teacher contracts and to the due process procedure upon termination or nonrenewal of a teacher’s contract do not apply to any supplemental contract of employment entered into under this section.