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Leadership Team

Merry Sorrells
Head of School

Taking the reins in 2022, Dr. Merry Sorrells brings more than two decades of extraordinary educational leadership experience to her role as Principia’s Head of School. For more than two decades, she has been in top leadership positions at private schools and executive leadership roles in education institutions including serving on a number of boards, the executive committees of the Independent Schools Association of the Southwest Association, and the Southwest Association of Espiscopal Schools, and the standards committees for both associations. Dr. Sorrells is committed to maintaining the highest standards of teaching and learning; developing student leadership, character, and community; and ensuring that Principia School students benefit from a relevant, hands-on, “future-ready” education that equips them for college, work, and beyond. 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. 

Merry Sorrells

Terry Grigsby
Assistant Head of School for Enrollment Management

An alum of the School, Terry joined the Principia leadership team in 2022 as the Assistant Head of School for Enrollment Management. Terry brings over 20 years of global experience, working in leadership with a focus on customer service, fiscal stewardship, operations optimization, and character education. Terry holds a BA from Principia College, and two master’s degrees, one in Procurement and Acquisition Management from Webster University, and the second in National Security and Strategic Studies (foreign affairs) from the United States Naval War College. Additionally, Terry completed Cornell University’s diversity and inclusion certificate program.

Terry Grigsby

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.

Tami Gavaletz

Christen Alford
Principal—Upper School

Christen Alford is the Upper School Principal and is primarily responsible for the academic programming for grades 9-12. She works closely with our Dean of Students and our Athletics Director to provide a premier Upper School experience academically, spiritually, socially, and athletically. Christen has over 30 years of experience in education and holds degrees from Principia College (BA, Secondary Education, and English), and a Masters in Educational Leadership from Maryville University. She is a credentialed teacher and administrator and holds a certificate in College Counseling from UCLA.

Samantha Dry
Principal—Middle School

Samantha Dry brings rich and diverse educational experience to her role as Middle School Principal from her nearly 30 years working in schools around the globe. Responsible for the day-to-day academic program for grades 6-8, she works to ensure an integrated, experiential approach to teaching and learning across Middle 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.

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.