Academic Team

All staff and teachers at Keystone are committed to making a difference in our students’ lives. They are knowledgeable, creative, caring, inspirational and highly qualified.  They communicate effectively with parents; but most importantly, they communicate effectively with each other and their students. In essence, they know their students well and are able to devote their attention to their strengths and areas of potential growth. As such, they focus on delivering a program that inspires students to participate, reflect, think critically, analyze, create and excel academically. Most important, they create classrooms where students can feel a sense of belonging, and develop programs that inspire learning and motivate students to want to come to school day after day.


Doa Demirsu-Doran, BSc, MBA

After completing her high school education in Canada, Doa continued her higher education at University of Massachusetts and graduated with a Bachelor of Science degree. After she returned to Montreal and worked for several years in the financial industry, she decided to pursue her passion for education. She completed her MBA at McGill University with a concentration in Global Strategy and Leadership. She has worked in curriculum implementation in international schools particularly in the adaptation of US (California) and Canadian (Ontario, PEI) curriculum. After working in various other management roles, she established the Keystone International Secondary School, serving both international and local students in Toronto. She is still heavily involved with McGill, acting as a director in the Toronto Alumni Association.

Academic Coordinator


Darlen Navarro, BSc

Darlen holds two undergraduate degrees, one in Telecommunications and Electronics Engineering and a Bachelor of Science in Applied Mathematics from York University, she imparts applicable knowledge and problem solving techniques on her students in her mathematics classes. Her teaching experience includes topics like Differential Calculus, Numerical Mathematics and Linear Algebra, as well as International Baccalaureate and advanced mathematics and physics from Grade 9 to 12. In addition, she holds an Advanced Diploma in Business Administration and Accounting from Sheridan College. Ms. Navarro is currently pursuing her Master of Mathematics for Teachers through the CEMC at University of Waterloo.



Stephanie Guerreiro, BA, BEd

Stephanie completed her Bachelors of Arts, History at Trent University and her Bachelors 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 experiencing different cultures.  She 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 worldviews and learn about the world around them. 

Sam Kim, BSc, PhD

Sam completed an Honours Bachelor of Science degree in Biology at Western University. He then graduated from University of Toronto, Department of Medical Biophysics with a Ph.D. degree in Science focusing on molecular biology and cancer research. Sam completed his Post-Doctoral training at York University in 2018. Sam’s research focuses on finding better non-toxic treatment for cancer patients. Sam has taught a biology course ‘Research Methods in Molecular Biology’ as a Course Director in 2015 and 2016, and a chemistry course ‘Introduction to Biochemistry’ as a Course Director in 2017 at York University. He is passionate about teaching and cares for all his students to do well in science and in life.


Radini Rajaratne, BSc

Radini completed an Honours Bachelor of Science at University of Toronto, where she studied Genetics and Psychology. She began her teaching career through various volunteer positions, including teaching children English as a Second Language in Sri Lanka, teaching music at a local community school, and hosting art workshops in Toronto. Having recently completed her degree, she is passionate about exposing students to the fun and intriguing side of the natural and social sciences whilst also teaching them skills that are essential in life. Radini believes that education is a lifelong process, and it is through education that we find the tools and the knowledge to navigate through the ever-changing challenges of this world.

Andie Warner, BA, BEd, MEd

Andie is a recent graduate of a Masters of Education in Social Justice Education and is passionate about teaching for social change. She also holds a BA in teaching English as a Second Language with a minor in English literature and a BEd in secondary education. Andie has a passion for international education, having studied abroad in Ecuador, France, and Germany, and as having taught in Monterrey, Mexico and several programs for international students in Canada. Andie views the arts as an excellent tool for fostering conversations about challenges faced by students and their communities, as well as mobilizing them with the skills and knowledge to advocate for positive change. 


Camille Cruz, BFA

Camille has experience in both the traditional and digital arts. She completed a Bachelors of Fine Arts at York University with high honours and soon after acquired a certificate for completing Sheridan College’s intensive 3D animation program with honours. Her passion for the arts had led her to a variety of creative opportunities. From working with multimedia art-focusing on portraits, photography, and as a 3D lighting artist for DHX media, which is considered to be one of the world’s leading independent kids’ content company. Camille is determined to pursue an opportunity to share her knowledge and passion with today’s youth. Along side teaching, Camille is currently also working as a freelance multimedia artist, but is also in the process of completing her new art series thats corresponds to women and mental health. She believes that Art is a great outlet for people to express themselves, no matter what experience they have. Whether it be to spark a light for a positive behavioural hobby or to assist in furthering a students art career, Camille commits herself to encourage and support her students to strive and reach their goals.


Taylor Berce, BA, MA

Taylor holds a Bachelor's of Arts from McGill University, where he studied geography, and a Master's degree from York University, where he studied linguistics. His broad variety of experiences as an educator include working as a librarian at McGill's cartography library in Montréal, teaching children in Guangzhou, China, and helping newcomers to Canada learn English in Toronto. Taylor sees learning a language as a holistic, lifelong process. Stemming from his Master's research, he is particularly interested in analyzing the use of language in "real world" contexts and the linguistics sub-discipline of corpus linguistics.   


Esra Perek, BEd

Esra has been a french teacher since 2004 for different age groups and learning needs. Graduated from Istanbul University with double major French teacher as well as elementary teacher, Esra believes that the main thing in learning a language is first to like it. To like it, a student has to get to know a few concepts like the culture and the country/countries that this language is spoken in. She also believes that every student has its own way to perceive the subject. Esra is trying to penetrate this knowledge into her classes and teach accordingly. She’s on a mission to teach with patience and perseverance and make the learning possible for everyone.


Rebecca Cornale, BA

Rebecca graduated from Queen’s University with an Honours Bachelor of Arts degree in Sociology, and a Minor in Art History. She is currently completing her Master of Social Work at the University of Windsor. Rebecca takes an anti-oppressive approach to education-social work by using innovative and diverse avenues to address each student’s unique needs. She believes in fostering a connection between education, self-regulation and social support. Rebecca’s academic interests include mindfulness and adolescent mental health. She has worked closely with youth in educational settings, and has experience developing experiential learning activities and outings based on the Ontario curriculum. Upon completion of her Master’s degree, Rebecca hopes to continue to work with youth and families within an educational setting.