This chapter presents two examples of citizen science initiatives in schools that took place in the outdoor environment and were developed from scratch by middle school science teachers. The teachers created their own research environments, research topics, and recruited scientific collaborators. They developed innovative curricula for teaching ecology that incorporates citizen science and conducted studies to assess the impact of their programs on their students. The teacher of the 8th-grade class aimed to diversify the learning environment for his low achieving students, provide them with novel experiences, encourage them to get to know their surroundings, and cultivate their interest in science. The teacher of the honors 9th grade science class aimed to teach through inquiry using an authentic research experience that was relevant to her students and could contribute meaningfully to science. These two examples demonstrate the potential of citizen science as a teaching strategy that provides students with opportunities to learn about science through authentic research experiences, develop scientific practices, and contribute to student scientific literacy. This chapter also discusses the design principles of citizen science in schools that took part in these projects which were developed by the Center for Citizen Science in Schools (Taking Citizen Science to Schools—TCSS). These principles can help teachers plan and implement citizen science projects that promote student learning effectively.