Formal schooling frequently lacks both democratic learning culture and effective climate change education (CCE). This study analyzes the effects of the participatory CCE initiative k.i.d.Z.21 and the impacts of the current Fridays For Future (FFF) climate protests on teenagers’ climate change awareness. The mixed-methods approach comprises online pre-and post-tests, and personal interviews with selected students. k.i.d.Z.21 follows moderate constructivist, inquiry-based learning approaches and addresses 14-year old students from secondary schools in Austria and southern Germany. Considering the effectiveness of the CCE intervention of school year 2018/2019 (N = 169), quantitative findings reveal an increased mean of major components of climate change awareness, including climate-friendly behavior. When separating participants and non-participants in Fridays For Future, personal concern and refusing meat have both increased significantly only among protest participants. A closer examination of this group identifies an enhanced feeling of self-efficacy that might be triggered by perceived collective efficacy. Besides, more climate-friendly consumption behavior, as well as enhanced multiplicative action, are detected. The interviewed students also clearly assigned increased action-related components of climate change awareness to the attendance of FFF. From the findings, we conclude that democratic learning in and out of school can enhance action-related components of climate change awareness, and a combination of both can have an even stronger effect.