Secondary Staff

Ms Schröder was born and raised in Almelo and has thoroughly enjoyed music since she was young. She started playing the flute and continued with the piano. She completed her Music Teacher Training at ArtEZ University of the Arts in Enschede, and taught at various schools before joining IST in 2025.

Her free time is also filled with music, as she is a member of different bands, playing the piano and guitar or singing. Her children also love music and are talented, so there is no shortage of music in her household.

She takes great pleasure in teaching music as she believes it is very important for the development of the students. It is wonderful to sing and play music with them, especially as they develop their skills and there is a sparkle in their eyes when they create music.

Ms Kolkman studied at the University of Twente, got her teaching degrees in Economics and Business Studies and finished a Masters degree at TIAS Business School of Tilburg University. She teaches Economics and Humanities at IST and serves as the DP Coordinator. Ms Kolkman feels that teaching is about giving students a broad and deep understanding of the world in which we live, and Economics gives us a good view on what people, firms and governments do. Her hobbies are textiles, arts and crafts, gardening and reading.

Mr de Haan joined the team in 2025 and teaches IGCSE and IB History. Having grown up in Twente, he has strong ties to the region. He is associated with both Het Stedelijk College Zuid and the International School of Twente (IST).

He completed his Bachelor’s degree in history teaching in Zwolle and is completing his Master’s in Amsterdam. Outside the classroom, he enjoys staying active through basketball and weightlifting. He is also an avid photographer, loves riding his motorcycle, and enjoys backpacking whenever he can.

In his teaching, Mr de Haan focuses on helping students use history to better understand the world they live in today.

Ms Serrano-den Breejen teaches IGCSE Chemistry to Year 10 and 11. She was born in Enschede and obtained a MSc degree in Chemical Engineering from the University of Twente. Before moving into teaching, she worked in Coatings Research and Development as well as Human Resources. She spent 17 years in England and the USA, where she worked as an AP Chemistry tutor as well as substitute teacher. Upon moving back to The Netherlands in 2022, she started teaching at IST and College Zuid and she obtained her first-degree teaching licence in July of 2024. She loves travelling, running, singing and showing students the different aspects of chemistry: exciting (sometimes explosive!) and interesting, but also logical and organised.

Ms Kellner teaches German from year 8 to DP2. She also supports Mother tongue learners (SSST) and students who choose to study additional subjects online (Pamoja). She is also the CAS Coordinator in school.

Ms Kellner grew up in Erfurt and attended the Universities of Jena, Göttingen and Groningen. She has a Master’s degree in European Culture and German Literature and Language as well as a Teaching Degree for Secondary Education. Before joining IST, she worked as a copywriter, translator and as a recruiter for a university. She also develops teaching material for an educational publishing house.

Mr Scheefhals joined the team at IST in 2017 as a teacher of Economics and as a mentor. He studied International Marketing and started his career as an investment advisor at a bank. After ten years, he switched careers and started teaching Economics and Management & Organization at Saxion university of applied sciences. Mr Scheefhals is excited about helping students to see connections between theory learned in class and experience Economics and Business in ‘real life’.

Ms Soeiro was born and raised in the United Kingdom and studied chemistry at Durham University. After completing a Master’s degree and spending one year working in industry, she moved to Switzerland where she obtained a Ph.D degree in organic chemistry from the University of Zurich. She has since worked and taught biology and chemistry in Brazil, Switzerland and The Hague, before joining IST. Ms Soeiro speaks English, Dutch, German and Portuguese and loves to work in a multicultural environment. She especially enjoys doing experimental work with students and teaches Chemistry and Sport, Exercise and Health Science at IST. 

In her spare time she enjoys exploring new places with her family, reading, embroidery, walking with friends and spending time in the garden.

Mr Erotas has a BA degree in English, a BA in Romance Languages and a MA in Foreign Languages from University of Delaware. He has worked in various schools in different countries. He has worked as a professor of  English for Academic purposes at the University of Twente and he has also taught in the Dutch school system. 

He has experience as an oral examiner for different Cambridge examinations  (FCE, CAE, and ECP) and he is an experienced IGCSE and IBDP teacher.

He enjoys helping students improve their English skills and realize their potential.  He enjoys the warm and yet multicultural environment of IST. In his free time he likes reading anything related to humanities (literature, anthropology, philosophy, history, human geography, psychology etc.)

Ms Sikkes teaches Biology in the IGCSE and DP programmes. She grew up in Friesland in the north of the Netherlands. She studied Biology and received her teaching qualifications from the University of Groningen. Afterwards, she moved to Enschede, where she taught Biology and biology-related subjects in different Dutch schools in both Dutch and English. She previously worked at a different international school as well as the Dutch part of Het Stedelijk Lyceum (College Zuid).

Ms Sikkes enjoys helping students to develop themselves. She challenges them to get more out of themselves than they thought they could.

Mr Woudwijk works at IST as the Visual Arts Teacher and IB exam officer. He studied Visual Arts and Design at ArtEZ Zwolle and has a passion for observing the world closely and helping students find out who they are and how they perceive the world. Having worked in a wide array of programs, Mr Woudwijk brings a wide and inclusive view on visual arts. First building a foundation by familiarising students with the formal elements of art, to later build on this and help students develop their own thoughts about the world around them.

In his free time, he enjoys painting, photography, reading, writing, playing the piano and running.

Mr Hofste teaches Sciences and IGCSE Physics. He studied Engineering Physics (BSc) at the Saxion Hogeschool and Applied Physics (MSc) at the University of Twente. He worked as an antenna engineer at Thales and did research (Ph.D) on how to utilize reflection and emission of microwave radiation for studying freezing/thawing processes in shallow soil. Now he enjoys teaching children and young adults to think like a physicist and to never stop questioning and testing your own ideas on “how stuff works”. When he’s not teaching, he enjoys reading (both fiction and non-fiction), gaming and singing the low bass in his choir (or an occasional soprano if the conductor isn’t paying attention).

Mr de Bruin holds a MSc in Economics and is originally a graduate of the academic World Teacher Training Programme at the University of Leiden. He is the IST Secondary Principal since August 2025.

He is well acquainted with international education, having started his educational career at a large school in Rotterdam teaching Economics and IBDP Global Politics. Since 2018, Mr de Bruin has gained extensive experience as a team leader and vice principal in different schools in the Netherlands and he is very pleased to be back in an international setting at IST.

Mr Stronks teaches Mathematics. He studied at the University of Twente (MSc Chemical Technology) and also obtained his teaching qualifications there.

Previously, he has been associated with the Stedelijk Lyceum Enschede for a long time as a Chemistry teacher and for the last 9 years as a team leader. Mr Stronks takes the position that every student has a talent and that this talent should be given space.

In his spare time, he enjoys travelling: he has already visited about 50 countries in the world, enjoys the many cultures and is happy to be able to experience them also at IST.

Ms Kelder teaches English in the Cambridge Lower Secondary years and supports students as Careers Counsellor, drawing on Master’s degrees in both Linguistics and Education. Having grown up in the south of Portugal, she has a naturally international outlook and values working in culturally diverse school communities.

Before joining IST, she taught in the IGCSE and IBDP programmes at an international school in Switzerland, where she also served as the IBDP Coordinator. These experiences strengthened her dedication to international education and its mission to nurture students who are reflective and open-minded. She is committed to guiding young people to discover their strengths, develop intellectual curiosity, and make informed choices about their future pathways.

Ms Kranenberg joined the IST in November 2024 as a Dutch teacher and Community Coordinator. Based in Enschede, she brings extensive experience in teaching Dutch language and literature at senior secondary level at schools in the Twente region. Ms Kranenberg completed her Master’s degree in Utrecht, where she developed a strong foundation in education and language instruction. Throughout her career, she has maintained a clear focus on student wellbeing and student support. She believes that effective learning can only take place in a positive classroom environment built on trust and engagement. She is dedicated to creating a supportive atmosphere where every student feels valued and motivated to achieve their potential.

Beyond the classroom, she is an avid reader and enjoys drawing in her spare time.

Ms Snijders teaches English language and literature. In addition, she has taken on the role of group 1 & 2 curriculum leader. She obtained a Bachelor’s degree in English Language and Culture and a Master’s degree in English Literature from Radboud University. Pursuing her interest in education, she completed a teaching degree in international and bilingual education at Utrecht University. She lived in the UK as a student attending Sheffield University through the Erasmus programme, and as a pre-service teacher in Wales. Ms Snijders is passionate about the IB programme and its holistic approach to learning. In her spare time, she loves to read and watch films and series. She is looking forward to making more time for painting and drawing.

Ms ter Heege is our Dutch teacher in the Secondary lower and middle years. She has studied in the US before accruing ample experience teaching Dutch at the primary school level in both Enschede and Rotterdam, and has subsequently spent 12 years teaching Dutch to expats in the Twente region. We are very happy that she brings this experience in teaching Dutch as a foreign language to IST.

In her free time, she loves to play padel, cook and read.

Mr Diekman received his Master’s degree in Marine Biology from the University of Groningen and his PhD in Evolutionary Biology from the University of Amsterdam. After working as a Postdoctoral researcher at the University of Faro, he moved back to the Netherlands to assist science classes with practical sessions and help students with their research.

Mr Galicza has been teaching Mathematics, Statistics and Data Science in a variety of institutions from secondary to graduate levels. Besides teaching, he has also been active in research. In particular, he holds a Ph.D (Summa cum Laude) in Probability Theory from Central European University. Apart from pure mathematics, he has also worked on industrial projects at the Technical University of Eindhoven and at ASML.

He is excited to teach at IST to share the beauty of mathematics with the students and show how it pops up in various places in our everyday lives. In his free time, he likes reading, hiking and playing chess.

Mr Diepenbroek teaches Physics at IST. He finished Electrical Engineering and his MSc in teaching Physics at the University of Twente and worked in Indonesia for nine years at an international school near the capital.

Mr Diepenbroek has a strong passion for his profession and believes one has never finished learning. He likes to show his students the wonders that nature has to offer and – through a ‘hands-on’ and ‘minds-on’ manner – scrutinise a myriad of these wonders.

In his spare time, he does his utmost to enjoy the wonders of nature himself, while hanging off rock walls (bouldering), or exploring the sea (scuba diving). He also spends his time on the mat doing Brazilian Jiu Jitsu.

Mr Lulof obtained his degree in Physical Geography and has been teaching Geography, History, Humanities and TOK at IST for many years. He is also a mentor teacher. He would like his students to learn to be polite and considerate to others and respect the differences between people. In his lessons, he encourages students to be inquisitive with respect to events in the world but also to be critical. ‘Your actions at school shape your future.’

Ms Jain is an urban and mobility planner and has two decades of experience working in the corporate, government and research sectors. She studied and worked in India and moved to the Netherlands 15 years ago. After completing her PhD, she continued her work here on sustainable urban development, delivered TEDx talks and also authored a book (which has been translated to Persian). She loves to work with young adults who are our future and believes that they have amazing ideas and solutions to world problems. She teaches Geography in the IGCSE and IB curricula at IST and is also a mentor teacher. You can find more information about her on www.yaminijsingh.com.