(a) The holder of a document authorizing day-to-day substitute teaching according to the provisions of Title 5 Sections 80025 and 80025.3 is authorized to serve as a substitute in a special education classroom; preschool, kindergarten and grades 1-12, inclusive; or in classes organized primarily for adults. However, the holder shall not serve as a special education substitute for more than 20 days for any one teacher during the school year.