"My Evidence" is a multi-user, multi-lingual online application developed for the Exploratorium project, "Evidence: How do we know what we know?" The goal is to engage online users by allowing them to examine how they themselves construct knowledge about the world. "My Evidence" begins by posing a statement on screen such as, "I believe the Earth is round." Users defend or refute the assertion by chronicling their own real life learning experiences, and in doing so produce a visual map of their personal "evidence" which can be stored, retrieved and revised by them. These evidence "quanta" can be categorized and weighted by the user, thus creating a visual reference tool which may be compared to other maps by other users. The application also collects minimal personal profile data (scientist/non-scientist, gender, age), opening avenues of inquiry into how people in diverse professions or stages of life might interpret their perceptions differently. We designed "My Evidence" to encourage self-reflection while providing a window into the kind of thinking that science requires.