This article reports on the rationale, implementation, results and evaluation of four rounds of co-creative Citizen Science (CS) projects (2021-2024) conducted with 10 public secondary schools in Opole, Poland. These educational interventions consisted in facilitating 18 team research projects designed and executed by 55 teenagers (15-17-year-olds) on topics related to communication, linguistic diversity, multiculturalism and language learning. The article shows how such interventions are conducive to pupils' increased language awareness, their reflectivity about the scientific methods in linguistics, and an inclination towards future citizen engagement regarding literacy-­related issues. The article also focuses on the potential of CS for allowing pupils themselves to enhance their language awareness and socio-linguistic competences while producing experiential and situated knowledge that is relevant to their communities. The project evaluation that was undertaken subsequently traces which learning outcomes are likely to be achieved during co-creative CS and recommends some adaptable tools for monitoring the increase in language awareness in secondary language education, also beyond the Polish context.