She is a former elementary and secondary school mathematics teacher. Dr. Kotsopoulos is a certified member of the Ontario College of Teachers. She is the co-developer of LittleCounters ®, a program aimed at supporting parents, caregivers, early childhood educators, and teachers in developing an understanding of early mathematical cognition. She is also the founding and co-Editor of the Fields Mathematics Education Journal. She is a member of the Canadian Mathematics Educators Study Group. Her interdisciplinary research focuses on mathematical cognition and mathematical teaching and learning across the lifespan, with a current focus on early childhood. Dr. Kotsopoulos has published in many prominent journals and has presented at conferences worldwide.