Sending kids home because their parents don't care enough to get them vaccinated or take a few minutes to fill out the exemption form is lousy policy. Haven't those kids been through enough?
If your kid hasn't been vaccinated, get it done, or at least complete the exemption. 
http://public.health.oregon.gov/PreventionWellness/VaccinesImmunization/GettingImmunized/Pages/non-medical-exemption.aspx#get