In this exploratory study, we report results from hosting two rounds of an open innovation competition challenging young people age 13-18 to develop a method for carbon mitigation. In both challenges, teams worked within the classroom and extensively on their own time out-of-school. The challenges were structured to engage participants to work collaboratively and independently in an open-ended, goal-oriented way, yet constrained their work by the parameters of the challenge, and supported it by a suite of tools, and resources. Evidence of learning science concepts and practices, student persistence, and the enthusiasm of participants, teachers and coaches, convince us that the Challenge structure and format is highly worthy of further development and investigation. Our findings indicate that Challenges such as this have the potential to enlarge the “ecosystem” of learning environments in the formal education system.