This research aims to reveal the negative impacts of out-of-school sources on history lessons and how teachers respond to these effects. The participants of the study are 20 history teachers who teach history lessons in secondary education institutions in Turkey. The research was conducted using a qualitative research method, and data was collected through a semi-structured interview form. According to the findings, the participants considered out-of-school sources to have slightly more influence on shaping students' historical consciousness compared to the school. In addition, these participants highlighted TV series and movies, family, and social media as significant factors. According to the participants, out-of-school sources can lead to negative effects on students, particularly by fostering misconceptions about historical processes, events, and figures, accepting incorrect information without questioning it, and rejecting the facts presented by teachers. Teachers' approaches to counteracting the negative effects of these out-of-school sources mostly involve presenting accurate information, guiding students toward reliable sources by providing specific references, and explaining the fictional nature of movies. In the study, it is considered that teacher approaches may not be sufficient in addressing the negative impacts of out-of-school sources, and thus various recommendations have been put forward.