The Washington state school directors' association shall adopt a model policy and procedure that school districts may use for granting waivers to individual students of up to two credits required for high school graduation based on unusual circumstances. The purpose of the model policy and procedure is to assist school districts in providing all students the opportunity to complete graduation requirements without discrimination and without disparate impact on groups of students. The model policy must take into consideration the unique limitations of a student that may be associated with such circumstances as homelessness, limited English proficiency, medical conditions that impair a student's opportunity to learn, or disabilities, regardless of whether the student has an individualized education program or a plan under section 504 of the federal rehabilitation act of 1973. The model policy must also address waivers if the student has not been provided with an opportunity to retake classes or enroll in remedial classes free of charge during the first four years of high school. The Washington state school directors' association must distribute the model policy and procedure to all school districts in the state that grant high school diplomas by June 30, 2015.