Courses that focus on local flora and fauna are no longer included in biology curricula; therefore most K-12 teachers lack the expertise to teach their students about local biodiversity. When teachers are unable to recognize the plants and animals in their own surroundings, threats to the environment and biodiversity will inevitably remain abstractions to students. In the summer of 2011, a five-day plant and insect biodiversity workshop engaging thirteen pre-service and in-service urban public school teachers and five undergraduate biology teaching assistants was held at a forest field station outside of New York City. The goals were to develop an appreciation of local plant and insect diversity amongst practicing and pre-service teachers, and prepare them to use outdoor experiences to teach urban students. Results from pre- and post-tests and surveys indicate that teachers made significant gains in their understanding of biodiversity, with the largest gains made on plant identification skills. Post-surveys, distributed six months following workshop completion, indicate that half of the in-service teachers used these resources in their classrooms. Responses also highlighted important intangible benefits of the workshop, and indicated that some participants used their new plant identification skills to identify or observe the street trees they pass as part of their daily routine.