Directory

Michele Santosuosso has served as a history teacher in the Department of History and Social Sciences since joining the St. Mark’s faculty in 2015. Mom to two Marksmen — Jacob ‘29 and Kane ‘32 — she advises multiple clubs and is the sponsor of the Upper School Student Council and co-sponsor for the ninth and tenth-grade class rotation. Previously, Santosuosso taught at Williams High School in

Mark Scheibmeir joined the St. Mark’s faculty in 2022 as a film studies teacher in the Fine Arts Department. He previously served as an arts educator and coach at OTM Acting Studio in Los Angeles and taught at the University of Texas at Austin. Scheibmeir maintains an active role in the entertainment industry as an actor, writer, director and producer. He sponsors the Film Club and serves as a ninth-grade adviser. He earned B.S. and M.F.A. degrees from the University of Texas at Austin. 

Kerry Schneidewind has been a member of the St. Mark’s faculty since 2012, serving as the assistant director of Admission and Financial Aid. She earned a bachelor’s degree from Oklahoma State University and a master’s degree from Southern Methodist University. Schneidewind previously worked in the office of Undergraduate Admission at Oklahoma State University and Southern Methodist University. She is a fifth-grade adviser. 

Lynne Weber Schwartz teaches A.P. Literature and Composition (12) and tenth grade English. She has held the Trustee Master Teacher Chair in Humanities for the past 20 years. Lynne sponsors the award-winning literary/art magazine The Marque and is the director of the St. Mark’s Teacher Institute. Before teaching at St. Mark’s, Lynne taught at Highland Park High School and the Mesquite Independent School District. For a number of years, she has served as lead consultant at a multitude of College Board A.P. English summer institutes in the Southwest. For seventeen years, she also served as a senior lecturer at The University of Texas at Dallas, teaching Curriculum and Instruction in English to pre-service teachers. In 2005, Lynne received the College Board’s Special Recognition Award. Lynne was editor-in-chief of the Laying the Foundation series of teacher guides and was the project director for the English Vertical Teams Guide published by the College Board. She holds a B.A. in History from UCLA and a Master of Humanities degree from The University of Dallas. Lynne is married and has a grown son and a daughter in Dallas, as well as a new granddaughter, Scarlett Rose.

Josh Shandera joined St. Mark’s in 2020 as Associate Director of College Counseling. A native of San Antonio, Josh earned his bachelor’s degree from the University of Texas at Austin before joining the UT-Austin Admission staff. During his tenure in UT admissions, Josh has served in a variety of roles, mostly recently as Admissions and Recruitment Coordinator for the Canfield Business

Holding two master’s degrees (in choral conducting and library and information services), Tinsley Silcox serves as both director of Library and Information Services and Upper School choir director. A native Tennessean, he has studied at  Carson-Newman University, the University of Tennesse and Harvard University’s graduate school of education. His former positions include director of Public Services for Central University Libraries at Southern Methodist University in Dallas, director of the Hamon Fine Arts Library and director of the G. William Jones Film and Video Collection at SMU. He has also served as director of the Blues Archives, music librarian and assistant professor at the University of Mississippi, and acting head of the George F. DeVine Music Library at the University of Tennessee. Silcox’s articles have appeared in such journals as Living Blues, Mississippi Libraries, Legends and Fontes Artis Musicae. He also serves the Dallas community as choirmaster at NorthPark Presbyterian Church.

Holder of the Malcolm and Melinda Brachman Master Teaching Chair, Dr. Martin Stegemoeller teaches courses in humanities to eighth graders. He earned a Bachelor of Arts degree from Northwestern University and a master’s degree and doctorate from Vanderbilt University. Before coming to St. Mark’s, Stegemoeller taught English and math, coached golf and tennis, was a dorm parent and did development work at Lake Forest Academy in Illinois. Before that, he was an assistant professor at the University of Alabama in Huntsville. He is the faculty sponsor for the Telos Leadership Society, the Upper School Philosophy Club and the Middle School Philosophy Club. Stegemoeller received the Franklin J. Machette Teaching Award from Vanderbilt University in 1993, the John H. Murrell Excellence in Teaching Award in 2007, and the Ralph B. Rogers Alumni Award in 2013. He has been chosen by the Senior Class to deliver the Baccalaureate address twice and was the Marksmen yearbook dedicatee in 2011.

Serving as organist and choirmaster, Glenn Stroh has been a member of the St. Mark’s community since 2011. He earned a bachelor of music degree from Trinity University, a master of music from the Oberlin Conservatory of Music in Ohio and a Aufbaustudium-A degree from the Hochschule für Musik Franz Liszt. Stroh has performed across the United Staes and Europe as a solo artist, accompanist and conductor. As a church musician, he has served numerous music programs including Saint Michael and All Angels Episcopal Church and the Church of the Transfiguration in Dallas, the historic Old Stone Church on Cleveland’s Public Square, and Trinity Cathedral of Cleveland. A recipient of the Fulbright Study/Research Grant based at the Hochschule für Musik Franz Liszt in Weimar, Germany Stroh sponsors SMacappella and the Organ Club and was a Ralph B. Rogers Alumni Award finalist in 2022. He received the John H. Murrell Excellence in Teaching award in 2017 and is a member of the Association of Anglican Musicians, the American Guild of Organists, Royal School of Church Music, the American Choral Directors Association and the Texas Choral Directors Association.

Mark Sullivan joined the St. Mark's School of Texas faculty in 1982 as the Lower School Physical Education Coordinator. Prior to his appointment as the Director of Athletics and Physical Education in 2000, Mark has served the school as the Wilderness Program Director, the Assistant Head of the Middle School and as a coach and teacher in the Athletic Department. Mark holds a Bachelor of Science Degree and a Masters Degree in Educational Administration from the University of North Texas, and is a recipient of the John H. Murrell Excellence in Teaching Award. Mark's coaching has included numerous Middle School sports as well as the Varsity Volleyball team and the Varsity Diving team.

Coming to St. Mark’s in 2016, Sherri Sullivan is the facility scheduler and receptionist for the School. She earned a Bachelor of Science in physical education degree from Colorado State University with an elementary certification for grades 1-8. Before coming to St. Mark’s, Sullivan was a teacher in the Dallas Independent School District for 25 years. She is an active participant in the School’s Wilderness Program, and has gone on 33 Pecos Wilderness trips.