Oregon Revised Statutes Education and Culture § 336.095

(2) Every school district that is not a union high school district must provide kindergarten facilities free of charge for the kindergarten children residing in the district by operating the facilities either singly or jointly with other districts or by contracting with public or private providers that conform to standards adopted by rule by the State Board of Education.

(3) Nothing in this section prevents a district school board from admitting free of charge a child who is a resident of the district and whose needs for cognitive, social and physical development would best be met in the school program, as defined by policies of the district school board, even though the child has not attained the minimum age requirement.

(4) Kindergarten that is offered as provided by subsection (1) of this section shall be funded in the same manner as other grades of the district are funded, except that the aggregate days membership of children in kindergarten shall be calculated as provided by ORS 327.006.

(5) Kindergarten is an integral part of the public school system of this state.