Doa Demirsu, BSc, MBA — Co-founder, Director
Doa Demirsu holds a Bachelor of Science degree from the University of Massachusetts and a Master’s in Global Leadership from McGill University, bringing an international and forward-looking perspective to school leadership.
Her vision for Keystone is rooted in the conviction that everything begins with the students — that education is not about filling minds, but about giving young people the tools to explore, question, and create meaning. At Keystone, this philosophy lives in every classroom: students are encouraged to be inquirers who take ownership of their learning, while teachers act as facilitators who guide, challenge, and inspire them to think critically and globally.
As an educator, entrepreneur, and parent, Doa is passionate about building learning environments that nurture both academic excellence and personal growth. She also serves as a Board Member at Waldorf Academy in Toronto.
Rachel Shiderman, OCT, MT, Hons BES — Principal
Rachel Shiderman earned an Honours Bachelor of Environmental Studies (Co-op) from the University of Waterloo, then a Master of Teaching from the Ontario Institute for Studies in Education, University of Toronto, where she dedicated her Master’s thesis to exploring the way teachers modify and adapt environmental programming for students with special needs.
Rachel first found her love for education in the outdoors, working in the K-12 space as an environmental education instructor for various outdoor education centres throughout the Toronto District and Durham Region school boards. She then began her classroom teaching career at The Dalton School, with a focus on K-8 Mandarin dual-language education, where over time she took on the role of English Department Head and eventually School Principal and Interim Head of School. In her most recent role, she supported the Principals and Vice Principals of The Bishop Strachan School, a K-12 private girls day and boarding school in Toronto, while leading the academic administration team through various process updates and school system advancements.
Rachel is a life-long learner who constantly seeks to better inform and add to her practice, collaborate with colleagues and extend herself to the interests of her school community, both in and outside of the classroom.
Stephanie Guerreiro, OCT, B.Ed, BA — Guidance Counsellor
Stephanie Guerreiro completed her Bachelor of Arts (History) at Trent University, and received her Bachelor of Education from Queen’s University. She spent the first five years of her teaching career working with students in Nanjing, China where she was able to explore her love of travel and experience different cultures.
Stephanie became a member of Keystone’s faculty as a Geography and History instructor in 2017. In 2022, she assumed the role of Academic Coordinator. In 2024, Stephanie transitioned into the role of Guidance Counsellor, where she continues to support students with academic planning, post-secondary pathways, and university and college applications.
Stephanie loves working with students from international backgrounds, as well as those from closer to home, as they all have stories and experiences to share that make the world more colourful and fulfilling. Her favourite courses to teach are History and Geography, as they give everyone in the class a chance to broaden their worldview and learn about the world around them.
Ece Öztürk, OCT, Hons BA, BMath — IB Coordinator
Ece Öztürk completed a Bachelor of Mathematics together with a Bachelor of Business Administration. She also holds a teaching certificate as well as a Master of Arts in Educational Administration and Supervision, which she completed with honours.
Ece became part of the Keystone team in 2016, teaching Math, and transitioned into the role of an Academic Coordinator in 2022. She is committed to the day-to-day success of all students and is always available for meetings with them to ensure that their time at Keystone is both enjoyable and productive.
Ece is passionate to share her love of learning with her students. She wants to instil a natural curiosity in the minds of her students so that they can find strategies to navigate today’s fast-paced world. She believes teaching is the first step in making a difference in this world – therefore, she wants to share her knowledge and experience with her students, wherever she is.
Heather Brown — Administrator
Heather Brown is a formally trained pastry chef, avid gardener and guinea pig enthusiast.
Having spent more than 10 years in the hospitality industry, she knows how important it is to feel safe, welcome, and cared for. At Keystone, Heather helps keep the day-to-day life of the school running smoothly and is often one of the first points of contact for students and families. From the first “hello” to the last “goodbye,” she brings warmth and kindness to every interaction and works to ensure that the Keystone experience feels easy, welcoming and familiar.
Sheron Prakasia, OCT, BEd, BSc
Sheron Prakasia is a passionate science teacher. She completed Bachelor’s degrees in both chemistry and education. She then completed her Master’s degree in chemistry from Mahatma Gandhi University, India.
Sheron strongly believes that education shapes an individual, not only in academics, but in their overall development. A teacher should help each child live in the outside world; teaching and learning is not something that is enclosed within books and school. Learning should be fun for students so that they will enjoy it instead of feeling burdened by it.
Sheron has experience teaching students with learning disabilities and she is ready to make any changes to her teaching style in order to achieve success for each child. She strongly believes that each child is important and that their learning needs have to be assessed regularly.
Steven Mesaros, PhD (ABD), MA, BA
Steven Mesaros earned an Honours Bachelor of Arts in Political Studies and a minor in Business from Trent University, followed by a Master’s in Political Science from York University, where he examined the restructuring of work in Canada since the 1980s. He continued his doctoral studies in Political Science at York University, achieving All But Dissertation (ABD) status. His research focuses on the evolution of concepts such as Economic Justice, Democracy, and Globalization, drawing on history and theory within the social sciences.
Steven’s extensive teaching career began with a decade in South Korea, where he taught students from kindergarten through Grade 12. In 2012, he transitioned to high school Social Science instruction, teaching a diverse range of courses, including Advanced Placement courses. He also served as a guidance counsellor, supporting students with university applications to institutions in Canada, the United States, and the United Kingdom. Steven also taught at York University as a tutorial leader and course director, teaching both introductory Social Science and upper-year American Politics courses.
In 2023, Steven joined Keystone, where he teaches a range of Social Studies courses and brings his extensive academic and international teaching experience to the classroom.
Alessia Franco, OCT, MT, MA, BASc
Alessia Franco completed a Bachelor of Arts and Science at the University of Toronto, with a double major in Criminology and Sociology. She went on to earn a Master of Sociology from Western University and a Master of Teaching from the Ontario Institute for Studies in Education (OISE) at the University of Toronto. Alessia is qualified to teach English and Social Science at the Intermediate/Senior level.
Through her teacher education and practicum placements, Alessia gained experience working with students across a variety of classroom settings. These experiences helped shape a teaching philosophy grounded in inclusive, differentiated and student-centred learning.
Alessia is passionate about creating positive classroom environments where students feel supported, encouraged to take risks and empowered to develop their literacy and critical-thinking skills. She believes that learning extends beyond the classroom and that strong relationships and a sense of community are important parts of student success.
Holly Hebert, MA, BA
Holly Hebert holds a Bachelor of Dramatic Arts with a Minor in Mathematics and a Master’s Degree in Theatre, Dance and Performance Studies. During her graduate studies, she explored how drama practices can be used in mathematics classrooms to create interactive lessons and collaborative learning environments. She put this research into practice during a placement at Keystone School, engaging Grade 7, 8 and 9 students in innovative math lessons, and later presented her work at the 2025 Children, Youth and Performance Conference. She returned to Keystone in 2026 and teaches math and science while also introducing drama into the curriculum.
Her experience working directly with students and families has developed a strong sense of attentiveness to individual learning needs. Through additional work as an administrative coordinator, she worked closely with students and their parents or guardians to better understand their learning styles and interests. She brings this same student-centred approach into the classroom.
Holly believes in creating welcoming classroom environments where students feel comfortable sharing their creativity, taking risks and communicating openly. She enjoys building collaborative learning spaces and incorporating interactive lessons that foster student confidence and curiosity.
Dylan Skurka, PhD (ABD), MA, BA
Dylan earned both his BA and MA in Philosophy at Western University, and went on to complete his PhD coursework and comprehensive exams in Philosophy at York University, achieving All But Dissertation (ABD) status.
With over a decade of experience working with students across a wide range of ages and backgrounds, Dylan is passionate about helping learners find their voice and reach their full potential. His teaching is rooted in an inquiry-based approach, encouraging students to ask questions, think critically, and engage in lively discussion.
For Dylan, education is less about memorizing facts than it is about learning how to think and connect ideas to the world around us. He believes a classroom should feel alive with curiosity—a place where different minds can meet, challenge one another, and grow together.
Gamze Kurunc, BA
Gamze Kurunc earned her Bachelor of Arts in French Language and Literature from Galatasaray University, with a focus on comparative linguistics and applied foreign languages. She also holds a Pedagogical Formation Certificate. As part of her studies, she spent a year on exchange at Université de Toulouse II – Le Mirail in France, further developing her knowledge of the French language and culture.
Gamze has nearly a decade of experience in education, working with students across a wide range of ages and backgrounds. She began her career as a French teacher and has taught French in a variety of educational settings. She later took on administrative roles, working closely with teachers, students, and families while supporting curriculum development and academic planning.
Gamze is passionate about language learning and the way languages can open students up to new cultures, perspectives, and ways of thinking. She believes that a positive classroom environment gives students the confidence to communicate, ask questions, and take an active role in their learning. She enjoys creating engaging lessons that encourage curiosity and help students connect what they learn in the classroom to the world around them.
Melanie Billark, BFA
Melanie Billark is a Toronto-based visual artist, art educator and creative community activator. She holds an Advanced Diploma in Crafts and Design from Sheridan College and a BFA in Sculpture and Installation from OCAD University.
Her environmental work has received recognition including The Climate Arts Award in 2019 and The OALA Ground Award in 2016. Her work has been shown and featured across the GTA and internationally, including with Breakfast Television, the David Suzuki Foundation, the Canadian Sculpture Centre, Pearson International Airport, Treefort Music Fest and Luminato Festival.
Melanie has more than 12 years of experience teaching and developing inclusive curricula for children, adults and seniors across a wide range of levels and abilities.
Shubhayan Kabir, MSc, BSc
Shubhayan Kabir earned his Master’s Degree in Applications of Mathematics at the Chennai Mathematical Institute in 2013 and went on to pursue independent studies in Machine Learning and Data Science.
With over 12 years of experience in Mathematics teaching and tutoring at various levels ranging from middle school to professional education, he incorporates his love for the subject with a passion for sharing and exchanging knowledge to create a unique learning experience for each of his students.
Shubhayan is a former candidate delegate for the World Cube Association, and his special skills and interests include board games, vocal music and being able to solve a Rubik’s Cube in under twenty seconds, single handed.
Inspired greatly by contemporary figures in Mathematics education such as Hannah Fry, Matt Parker and Grant Sanderson (3Blue1Brown), he is strongly committed to fostering a culture where every individual feels a sense of belonging and where diverse voices are amplified and celebrated.
Academic Guidance
Keystone School provides personalized academic guidance to help students navigate their educational journey. Our dedicated advisors work closely with students to select courses, plan for university admissions, and achieve their academic goals.
IB World School
Keystone School is proud to be an IB World School authorized to offer the International Baccalaureate (IB) Diploma Programme (DP). At Keystone, students can pursue the full IB Diploma Programme or take a few IB courses. Learn more about our IB Diploma Programme.
News & Updates
Stay informed with the latest news and updates from Keystone School. From student achievements to upcoming events and exciting developments, this page keeps you connected to everything happening within our school community.
