This study illuminates teachers' conceptions of gender and science and possibilities to challenge these conceptions. Since 2005, a group of teachers (K-6) in Sweden have met approximately once a month in two-hour seminars to discuss and develop their instruction in science and technology based on a gender perspective. The present data consist mainly of audio-recordings of the teacher seminars and video-recordings of science activities with students. Analysis of the empirical data has been carried out in several stages and was inspired by thematic analysis, the theoretical framework of which is based on Hirdman's and Beauvoir's theories of gender. The results show that the teachers' ideas about gender/equity and science exist on several levels, within which various conceptions are represented. On the one hand, "reasoning around similarity", where teachers consider that both girls and boys should have the same prerequisites for working with science. In contrast, stereotypical conceptions of girls and boys occur when the teachers evaluate their activities with students, and condescending attitudes toward girls are also observed. The girls' ways of working with science are not as highly valued as the boys', and this outlook on children can ultimately have consequences for girls' attitudes towards the subject. When teachers are allowed to read their own statements about the girls, they get "a glimpse of themselves", and their condescending ideas about girls are made visible. In this way, the teachers can begin their active work towards change, which may lead to new outlooks on and attitudes towards students.