Questions and issues related to ethnic diversity are part of the everyday experiences in Canadian classrooms. Most scholars and educators in the field assume a progression from knowledge of diversity, through to acceptance, respect, and justice. Knowledge about difference is not enough, but it is the starting point for both respect and justice. And yet, there is almost no research on how young people or teachers understand ethnic diversity. If we do not understand what makes us similar and what makes us different, the decisions we make (in the classroom, on the playground) are based on assumptions, not knowledge--and what you don't know can hurt me. (Contains 14 endnotes.)