As used in this chapter, "volunteer" means an individual not employed by a school district, educational service district, the Washington state center for childhood deafness and hearing loss, the state school for the blind, charter schools established under chapter 28A.710 RCW, school that is subject of state tribal education compact under chapter 28A.715 RCW, Bureau of Indian Affairs funded school, approved private schools, and their contractors who will have regularly scheduled unsupervised access to children under eighteen years of age or developmentally disabled persons, during the course of his or her involvement with the school or organization under circumstances where access will or may involve the following:

(1) Groups of five or fewer children under twelve years of age;

(2) Groups of three or fewer children between twelve and eighteen years of age; or

(3) Developmentally disabled persons.