Please go to http://www.cupertino.ca.campusgrid.net/. Click on Parcel Tax link (on the right hand corner) which will bring you to Exemption Information. Click on Senior Citizen Exemption link and you should be able to find a form that you can print and fill out.
The Foothill Unified SD...what city is your property located for this SD?
If you want you can call me at 408 636 3806 and I will be able to assist you further.
The Cupertino Union School District office is located at 10301 Vista Drive Cupertino, CA 95014. Their phone number is (408) 252-3000. For "Foothill" you may mean Fremont Union High School District. They can be reached at (408) 522-2200 and their office is located at 589 W. Fremont Avenue, Sunnyvale, CA 94087.
Hopefully, that will help you obtain the necessary applications to become exempted from the parcel taxes. Let me know if you have any questions or need help.