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Management & Board

The leadership team at BBIS is committed to upholding the school’s values – we strive to be pioneering, caring, reflective and excellent.


Our leadership team is comprised of a Supervisory Board (elected according to our by-laws) made up of business, community and education leaders, parents, and two managing directors. The school’s Director and CEO is responsible for leading and ensuring the continuing high quality of our educational programmes; while our Business Director and CFO is responsible for administrative and financial management.

The principals of the Primary and Secondary Schools, as well as the heads of Student Support Services and Boarding, round out our management team. Meet them all below.

Management Team


Mark Hardeman joined the BBIS community as Director in August 2023. With over 20 years of experience in international education, Mark has previously worked in Kuwait, Abu Dhabi and Beijing, and Dar es Salaam. He is a strong advocate for personalising education and believes that all students should have opportunities to explore and develop their passion for learning. Mark's educational credentials include a Doctorate of Educational Leadership from Lehigh University. In addition, Mark holds a Masters of Educational Leadership degree from the University of Wollongong, Australia and Bachelor of Arts and Education degrees from the University of Windsor, Canada.

Business Director/CFO

Burkhard Dolata joined BBIS as CFO in January 2004. He holds a degree in General Business Administration and a German Business Diploma (Diplomkaufmann). Previously, he worked as Executive Software Specialist and Finance Director for international computer and technology companies. Until 2003, he was an Executive Board Member of a Residential Building Corporation in Berlin. Burkhard was born and raised in Germany, is married and has four children.

Primary School Principal

Beth Dressler brings a diverse perspective given her experiences working in independent and international school settings in Thailand, the United States, Australia, Malaysia, Indonesia, and Germany. For the last twenty years she has worked in International Baccalaureate schools and is a long standing IB Primary Years Programme workshop leader, consultant and visiting team leader. She holds a Master’s Degree in Teaching English to Speakers of Other Languages (TESOL) from Michigan State University, a Certificate of Educational Technology and Informational Literacy (COETAIL), and holds a certificate in international school leadership from the Principal’s Training Center. Beth is committed to international education in Germany and serves on the Board of AGIS (Association of German International Schools). She lives in Potsdam with her family.

Secondary School Principal

Trixie Siemens joined BBIS after working in schools in Canada, China, Romania and Tanzania. She completed her undergraduate studies at the University of British Columbia in Canada, and holds a Masters of Arts in Educational Leadership from the University of Bath in the UK. She began her teaching career in the field of science and was an IB DP Examiner and IB MYP Moderator for the Personal Project. Currently, Trixie serves as a chair for international accreditations for both New England Association of Schools & Colleges and the Council of International Schools, giving her an opportunity to support educational review and development for schools around the world. Trixie is passionate about supporting holistic student development.

Deputy Secondary School Principal

Dan Stiles joined BBIS in January 2015 to work in the Science Department. He studied Biochemistry in Manchester, and has a PGCE in secondary science education. Dan has held a number of positions at BBIS, including Teacher of Biology and Chemistry, Duke of Edinburgh’s International Award Coordinator and IB MYP Curriculum Coordinator. He is now the Deputy Secondary School Principal with a focus on student wellbeing, behaviour management, and student life. Dan values the importance of building relationships with students, parents and teachers, and will often be found out of his office talking to our students. He is married with a young daughter and dog, and they live in Berlin.

Head of Student Support Services

Jonathan Matthews-Hirsch (BA Hons, PGCE, MSc) joined BBIS in 2009 and has a career in education spanning over 20 years with the last 10 dedicated to the area of student support and special educational needs. In that time, Jonathan has taught in a variety of educational establishments ranging from mainstream schooling to special education, from Kindergarten to university level, and in diverse locations including London, Prague, Manila, Brighton and Berlin. In addition to heading the Student Support Services, he serves as Learning Support Coordinator.

Head of Boarding

Steve Crossley joined BBIS in January 2021 as Head of Boarding, having previously worked in boarding schools in the UK, Austria and the United States. Steve is a level 3 boarding practitioner and holds the BSA Boarding Management diploma, in addition to a BA in politics and history from Salford University and a PgDip in pastoral care, guidance and pupil support from the University of Aberdeen. Steve is married with two daughters.

Director of Technology

Maryam Ferdosi joined BBIS in 2019, transitioning from her previous roles in Dubai where she was involved with the British curriculum and International Baccalaureate schools as the Head of the ICT Department, Innovation Leader, and Computer Science/ Design Teacher. Additionally, she has also contributed as an IB DP Examiner. Maryam holds a Bachelor’s degree in Computer Engineering and a Master's degree in Information Systems Management from the University of Salford. Her approach to integrating technology in education reflects a thoughtful and continuous learning journey, which she has carried into her current role at BBIS, helping to enhance educational experiences through technology.

Supervisory Board
Dr. Frank H. Walter-von Gierke (Chair)
Attorney-at-Law from Germany (Potsdam), three children at the school 1996-2016, board member since 2001.
Markus Beran
Banker from Germany, one child at the school, board member since 2013.
Dr. Martin Hintze
Entrepreneur from Germany, two children at the school, board member since 2021.
Prof. Dr. Daniel Koerfer
Historian from Switzerland, teaching at the FU Berlin, two children at the school 1996-2009, board member since 2015.
Ira Philip
Business consultant and financial analyst, two children at the school, board member since 2023.