Each school board shall provide not less than 12 consecutive years of appropriate instruction and special services for exceptional children, beginning with those six years of age, in accordance with the provisions of this chapter. Such public school instruction and special services shall be made available at public expense for each school year to exceptional children as provided herein. The funds for such instruction and special services shall be derived from state, county, municipal, district, federal or other sources or combinations of sources. Each school board shall set aside from its revenues from all such sources such amounts as are needed to carry out the provisions of this chapter, if such funds are available without impairment of regular classes and services provided for nonexceptional children. If sufficient funds are not available to a school board to provide fully for all the provisions of this chapter as well as the educational needs of nonexceptional children, such board must prorate all funds on a per capita basis between exceptional and nonexceptional children. No matriculation or tuition fees or other fees or charges shall be required or asked of exceptional children or their parents or guardians, except such fees or charges as may be charged uniformly of all public school pupils.