Directory

Beginning his St. Mark’s career in the Office of Admission, Dean Clayman transitioned to administrative posts in the Middle School office in 2012, first as assistant head. He then was appointed Middle School head in 2017, a position he currently holds. He has a Bachelor of Arts degree from the University of Colorado at Boulder and a Master of Arts degree from California State University-Dominguez Hills. Clayman started teaching as a member of the Teach for America Corps. While in southern California, he taught grades 1, 3 and 4 as well as serving a technology resource teacher and language acquisition specialist. Subsequently, Clayman served as the coordinator of professional development for school districts as well as for the Orange County Department of Education. Upon moving to Texas, Clayman served as a technology teacher, teacher of leadership and director of admission at independent schools in Dallas. He’s the father of two Marksmen, Sam ‘17 and Ben ‘18.

Greg Crook was appointed to the Thomas S. Adams Master Teaching Chair in 2021 and serves as a seventh grade humanities teacher. He earned his Bachelor of Arts degree from the College of William and Mary. Before joining St. Mark’s, Crook taught history at the Episcopal School of Dallas. In addition to serving as a seventh-grade adviser, Crook is co-coach of the Middle School Academic Team and is a co-coordinator of the Middle School Community Service program. He received the John H. Murrell Excellence in Teaching Award in 2020.

Cynthia McMahon joined the St. Mark’s faculty in 1990 and currently serves as a fourth-grade humanities teacher. McMahon earned her B.S. and M.Ed. degrees from Stephen F. Austin State University. She taught elementary grades in Nacogdoches, Berkeley, CA and San Francisco before arriving at St. Mark’s. In 1993, McMahon received the Murrell Excellence in Teaching Award.

Reilly Walker has been a member of the St. Mark’s faculty since 2020 and teaches seventh grade humanities. Before joining St. Mark’s, she taught English at Stuart Hall High School in San Francisco and at the Lycée Français de San Francisco. Walker earned two bachelor’s degrees from Marquette University and a master’s degree from Middlebury College. Reilly serves as a seventh-grade sponsor and advisor and sponsors the Middle School Green Team