Leadership Team

  • Celia Sosa
    Celia Sosa
    Executive Director
  • Stephen Trowbridge
    Stephen Trowbridge
    Chief Financial & Operating Officer
  • Lex Zain
    Lex Zain
    Chief Academic Officer
  • Valarie Hunsinger
    Valarie Hunsinger
    Director of Development & Marketing
  • Liz Martin
    Liz Martin
    Special Education Director
  • Christine Moloughney
    Christine Moloughney
    Elementary School Director
  • Ada Garcia
    Ada Garcia
    Middle School Director
  • Matthew Hittenmark
    Matthew Hittenmark
    High School Director
Celia Sosa
Executive Director

Celia Sosa is Executive Director after spending her twelfth year as High School Director followed by three years as a Hyde classroom teacher. She participated in the Charter Center’s Principal Support Network and was awarded an Emerging Leader Fellowship for the 2009 – 2010 school year. During her time at Hyde, she has been involved in developing curriculum, chairing the social studies, science, language departments, and many extracurricular activities. Some of these activities included developing and organizing the Dynamics of Difference Committee, student interview panels, wilderness trips, and coaching the school track team.

Before joining Hyde, Celia worked as a teacher at The Lorge School and The Urban Assembly School of Business for Young Women. At each organization, she took on a leadership role becoming a Director of School Culture and Dean of Students. Additionally, while at Binghamton University, Celia was a co-founder of the local chapter of INCITE! Women of Color Against Violence. She has her Bachelor of Arts and Master of Arts in Philosophy from Binghamton University and was awarded the Clifford D. Clark Fellowship for work on her master’s degree. She received a second master’s degree in education with a concentration in adolescent social studies from Pace University. Celia was a 2005 Teach For America corps member.

Stephen Trowbridge
Chief Financial & Operating Officer

As Chief Financial & Operating Officer, Stephen has responsibility for all non-instructional operations of the school and is a member of the Hyde Senior Leadership Team. Before joining Hyde Leadership Charter School, Stephen was Chief Operating Officer of TurtleBay Advisory Services LLC, a business advisory firm in New York City, which provided project management and business transformation expertise to the financial services industry. At TurtleBay, Stephen was the senior financial officer and oversaw human resources, vendor and contract management, and customer experience. Stephen is a skilled manager of financial operations and has held senior executive positions at both world-class banks and asset management firms, including The Capital Group Companies, Mellon Financial Corp., and Bankers Trust Co.

Stephen is dedicated to educating children and is especially passionate about providing all children with equal access to excellent schools. He is currently a Trustee at Manhattan Country School, a progressive, mission-based school in New York City founded by his parents over 50 years ago. Stephen is a graduate of Connecticut College, where he majored in government and English. He is a native New Yorker, where he currently lives with his wife and son.

Lex Zain
Chief Academic Officer

Lex is currently Chief Academic Officer after her ninth year as Middle School Director. She received an undergraduate degree from Middlebury College and two master’s degrees from both Pace University and Columbia University. Lex holds her master’s degree in Education and a New York Principal Certification.

In addition, Lex has experience as a classroom teacher and has held other school leadership positions. She began her career in education as a Teach For America corps member, followed by years of experience as a teacher, dean, and school director. Lex joined the Hyde Senior Leadership Team in 2012.

Valarie Hunsinger
Director of Development & Marketing

Ms. Hunsinger joined Hyde Leadership Charter School as Library Media Specialist in 2009. Over the past nine years, Ms. Hunsinger built a school library, expanded literacy, and technology opportunities for students, coached the Hyde Debate Team, led the NYC Junior Ambassador Program, and founded the Hyde Tech Team. In 2017, Ms. Hunsinger transitioned to become the school’s Director of Development and Marketing.

Ms. Hunsinger serves as an advisor to the Bisila Bokoko African Literacy Project. She is a member of AASL and a member of the ALA International Relations Committee—Africa Subcommittee. She has written for  School Library Monthly, Knowledge Quest, and International Leads. She is also an executive committee member for the Day of Knowledge Conference in the Dominican Republic. Ms. Hunsinger has a BA in International Affairs from Lewis & Clark College. She was a recipient of the Laura Bush 21st Century Librarian Program Scholarship and in 2013 she received her MA in Education and School Library and Information Technology from Mansfield University.

Liz Martin
Special Education Director

Liz Martin joined the Hyde team in 2006 as a founding teacher and Special Education Coordinator. She currently serves in the role of Special Education Director, overseeing Hyde’s Special Education program K-12. She is a fierce advocate for inclusive education and works closely with the leadership team to ensure Hyde is developing as an inclusive organization. Prior to working at Hyde, Liz started her career as a Special Education Teacher in Louisiana with the Teach For America 2002 Greater New Orleans corps; she also taught in Brooklyn and Harlem both in traditional and charter schools. Over the years, Liz has worked with students with a range of disabilities in varied settings. Liz received her undergraduate degree from UNC-Chapel Hill, and her Masters in Special Education at Queens College. In her spare time, Liz enjoys swimming, reading, drawing, hiking, and photography/videography.

Christine Moloughney
Elementary School Director

Ms. Moloughney joined Hyde Leadership Charter School as a K-8 Technology teacher in 2008 following an information technology career in higher education. After serving 3 years in the classroom, she was selected as an Emerging Leadership Fellow with the New York City Charter School Center for 2012-2013. This program focused on leadership development by guiding leaders through rotations in school culture, community engagement, recruitment, accountability, and school finance. After completing this program, Ms. Moloughney took on the role of Dean of School Life K-5, where she worked to ensure that the programs, activities, and day-to-day operations of the Elementary were aligned with Hyde’s mission. This included onboarding new teachers, leading staff professional development, teacher observations, and maintaining school culture through weekly school meetings,  a discovery group curriculum,  and special events.

In the fall of 2020, Ms. Moloughney began her thirteenth year at Hyde. She is a graduate of Pace University where she earned her Bachelor of Arts in Literature and Communication and a Master of Science in Teaching as an Educational Technology Specialist.

Ada Garcia
Middle School Director

Ms. Ada Garcia joined Hyde in 2014 as a middle school English Language Arts teacher through Teach for America and has held several roles, including classroom teacher, interventionist, department chair, grade-level lead, and instructional coach. She received a Bachelor of Professional Studies degree in Human Services from the Metropolitan College of New York and a Master of Arts degree in Middle School Education from the Relay Graduate School of Education.

Ms. Garcia is from the Dominican Republic, but has been a Bronx native since the age of two, and is eager to give back to the community that raised her by improving the quality of education our children receive. She understands that the transition to middle school is critical when it comes to a child’s emotional, social and academic well-being, and is committed to ensuring our students receive a top-quality education while also enjoying the beauty of simply being kids.

Matthew Hittenmark
High School Director

Since joining Hyde Leadership Charter School as a Health and Physical Education teacher in 2006, Matthew Hittenmark has consistently demonstrated his commitment to making a positive impact on Hyde’s students. During his first position at Hyde, Mr. Hittenmark developed the curriculum, assessed student mastery, and instructed physical education for grades K-10. After serving six years in the classroom, he transitioned to serve as Hyde’s Director of Athletics and Youth Development. Through this position, Mr. Hittenmark coordinated internships, led community service projects, and managed the arts, P.E., safety, and security at Hyde. Shortly after, Mr. Hittenmark became the Dean of School Life to ensure that all operations aligned with Hyde’s mission. Mr. Hittenmark then became Hyde’s Director of College Counseling & Post-Secondary Success, during which he guided students through the transition from high school graduation to post-secondary education. After four successful years working in post-secondary success, Mr. Hittenmark became Assistant High School Director, overseeing an expansion of our Advanced Placement Program to include AP Computer Science Principles and AP Capstone.  He has now assumed the role of Hyde’s new High School Director. In the summer of 2021, Mr. Hittenmark began his sixteenth year at Hyde.

Mr. Hittenmark graduated from Marist College earning his Bachelor of Arts in History. Mr. Hittenmark continued his education and earned a Master’s Degree in Public Administration from Baruch College and a Master’s Degree in Adolescent Special Education from Hunter College. He has also attended the National Institute for Urban School Leaders at Harvard University.