Leadership Team
Terry Grigsby
Head of School
Terry Grigsby, a proud graduate of Principia School (’97) and Principia College (’01), returns to his alma mater with a lifelong connection to the School and a deep commitment to its values. As a current Principia parent and seasoned educational leader, Terry brings both personal insight and professional expertise to his new role as Head of School.
Since 2022, Terry has served as Assistant Head of School for Enrollment Management and Residential Life, leading strategic efforts that have strengthened admissions, enhanced the boarding experience, and supported student care and international student programs. His work has helped shape a vibrant, inclusive community grounded in Principia’s values and designed to meet the needs of today’s students.
Terry’s path to school leadership was shaped by a distinguished 20-year career as a commissioned officer in the United States Navy. He held leadership roles on five continents, known for building high-performing, mission-focused teams rooted in trust, accountability, and service.
Terry holds a B.A. in Business Administration from Principia College, an M.A. in Procurement and Acquisition Management from Webster University, and a second M.A. in National Security and Strategic Studies (Foreign Affairs) from the U.S. Naval War College.
With a deep respect for Principia’s heritage and a forward-looking vision for its future, Terry is committed to preparing students to lead lives of purpose, service, and spiritual depth in a complex and changing world.
Tami Gavaletz
Assistant Head of School for Business and Operations
Tami Gavaletz brings a wealth of institutional knowledge, management skills, and steadfast dedication to serving our students and families in her 20 years of working in school operations and enrollment management. After successfully serving as Interim Head of School for a year, she moved into the role of Assistant Head of School for Business and Operations to enhance the current leadership structure, support the School’s continued growth, and elevate key institutional goals. Tami holds an MA in Legal Analysis from Webster University and BA from Principia College.
Samantha Dry
Principal—Upper School
Samantha Dry brings rich and diverse educational experience to her role as Upper School Principal from her nearly 30 years working in middle and upper schools around the globe. Responsible for the day-to-day academic program for grades 6-12, she works to ensure an integrated, experiential approach to teaching and learning across Middle and Upper School disciplines, fostering global awareness and future-ready skills in students. Samantha holds an MA from the University of Southern Queensland, Australia, and a BA from the University of South Africa.
Merry Sorrells
Principal—Middle School
Dr. Merry Sorrells brings more than two decades of extraordinary educational leadership experience to her role as Middle School Principal. Dr. Sorrells previously served as Head of School for Principia and has been in top leadership positions at other private schools, including executive leadership roles in education institutions. She also served on a number of boards, the executive committees of the Independent Schools Association of the Southwest, and the Southwest Association of Episcopal Schools, as well as the standards committees for both associations. Dr. Sorrells is committed to developing student leadership, character, and community; and ensuring that Principia School students benefit from a relevant, hands-on, “future-ready” education. She holds an Ed.D in Executive Leadership from the University of Holy Cross, a Master’s in Educational Administration from the University of New Orleans, and a B.A. in International Relations from Principia College.
Heather Tibbetts
Principal—Lower School
Heather Tibbetts leads our Kindergarten through grade 5 program as the Lower School Principal. She has been in education for almost 20 years as a classroom teacher, learning specialist, and school administrator at the elementary level. She focuses on providing engaging academics, a positive learning community, and opportunities for character growth for all students. She holds a BA in Elementary Education from the University of Michigan and an MS in Curriculum & Instruction from Missouri Baptist University. She also has a certificate in School Management and Leadership from Harvard University.
Dorothy Halverson
Principal—Early Childhood
Dorothy Halverson has a deep love of young children and an inspired commitment to their formative learning experiences. With skills and empathy gained over more than 30 years of teaching at the elementary and kindergarten levels and leading the Early Childhood program as an administrator, she supports new parents and their infants and toddlers in our Acorn Programs and in our Early Learning Center. Dorothy holds a BA from Principia College and an MA in Educational Leadership from Maryville University.
