Microplastics are ubiquitous. Therefore, it is a highly topical research field due to the different impacts on ecosystems, which arise from them. Despite its enormous fundamental importance and the extensive media presence, microplastics are still too little present in the school context. Therefore, the BMBF project PLAWES surveyed university students on the topic of microplastics. In this study, we gained insights into students' conceptions on the term microplastics, possible sources in the household, risk assessment, potential consequences, and their sources of knowledge on the topic. For this purpose, 267 university students (56.6 % female) with an average age of 20.3 (SD = ± 2.56) years responded to open and closed questions. These were subsequently analyzed in utilizing a qualitative content analysis. 78 % of the respondents classified the term microplastics with reference to small plastic particles. As sources of microplastics in the household, plastic packaging was mentioned by 43 %, followed by cosmetic products (28 %) and diverse plastic objects (19 %). Furthermore, in the context of microplastics, students showed a great threat awareness: 36 % classified microplastics as very dangerous, and 55 % as dangerous, but 19 % could not reason their assessment. Media is the most crucial information source: 51 % of the respondents cited different media channels (e.g., TV, internet, print media). More reliable sources of information such as schools (named by 21 % of the respondents) and projects (4 %) have less importance in the procurement of information. It is precisely this frequency pattern that shows the great need for action in schools to form students' conceptions in a well-founded way and to close knowledge gaps on the subject of microplastics.