Go back to directory. Add to Address Book. Mr. Jon DeRock Varsity Basketball Coach Junior/Senior High SchoolWinthrop Work 302 N. Cottonwood St. PO Box 1001 Sibley Winthrop MN 55396 USAwork Email: jon.derock@gfwschools.orgINTERNET Categories: Coach/Advisor, Junior/Senior High School Updated 1 year ago. Share on