Upper School Teachers

Robert Loren Thoburn

History, Government, Economics
OH Since 1997

Robert and his wife, Sheila, belong to Reston Bible Church. In 1997 they founded OH and have seen 6 of their grown children graduate from the school. Their 3 youngest still attend. Robert earned a B.A. in business and Austrian economics at Grove City College and a J.D. from Pepperdine University School of Law.

Heather Yarashus

OH Since 2022

Heather Yarashus, B.A. in Chemistry and M.A. in Chemistry from William and Mary, worked as a homeschool science teacher for many years and as a substitute at Chesapeake Bay Governor’s School. She has 8 children and is a member of Sterling Orthodox Presbyterian Church.

David Sabin

PE, History, English, Bible
OH Since 2016

David Sabin was born into a family of missionaries. He speaks fluent Spanish and participates in music ministry and prayer team at Grace Tabernacle Church in Ashburn. Mr. Sabin has 4 sons and holds a B.S. in English and Spanish Education and an M.A. in Administration from Pensacola Christian College.

Seth Thoburn

OH Since 2018

Seth Thoburn enjoys just about any language: Latin and Hebrew as well as math and programming which he also considers to be languages. Seth is a full stack developer at ConsignCloud and graduated cum laude with a B.A. in Liberal Arts and Culture from New Saint Andrews College.

Zachary Aardsma

Math, Science
OH Since 2021

“Mr. Z” works as an upper school co-teacher and also teaches Calculus and Algebra. He pursues math and science, and he studied molecular biology at the University of California, Santa Cruz and Houghton College. He enjoys tennis, mountain biking, golf, pickleball, swimming, drawing, and painting. He and his wife attend Cornerstone Chapel, and they are expecting their first child in September.

Sheila Key Thoburn

Literature and Writing
OH Since 1997
IEW Registered Instructor

Sheila Key Thoburn was influential in creating a classical curriculum at Oak Hill over the years. She grew up in Arlington, studied biology and paramedics, and is a great mother to her and Robert’s children. She thoroughly enjoys reading almost any book and, when she can, runs her own Etsy Shop. She is also a registered instructor with the Institute for Excellence in Writing.

Claudia Key

OH Since 2005

A native of Northern Virginia, Claudia Key grew up in Christian schools. She studied voice, piano and art. Mrs. Key speaks fluent Spanish and is a very engaging teacher. She has 4 children, 4 grandchildren and attends Reston Bible Church with her family.

Arelis Gil

Athletic Director, College Counselor
OH Since 2014

Arelis Gil earned a B.S. in Education and an M.Ed. in Curriculum and Instruction from the University of Nevada, Las Vegas. She spent six years as an instructor at Palo Verde High School in Las Vegas and has experience teaching honors history, AP and other courses. She has 3 children at OH and attends Centreville Baptist Church.