The Swedish preschool educational tradition is based on a holistic view where care, play, learning, and teaching are intertwined. Previous research argues for the need to develop teaching approaches that simultaneously direct attention towards content and children's perspectives. The aim of this study is to contribute with knowledge about how preschool children's agency is supported in activities that integrate play and science, with a special focus on the use of representations. The empirical data consists of video-observations of teachers' and children's (2-4-years) participation in activities that integrate play and science. In the analysis, the theoretical framework of Play-Responsive Early Childhood Education and Care (PRECEC) is used. Here, teaching and play are understood as a mutual activity. In these mutual activities, teachers and children are constantly shifting back and forth between "as if" (fantasy) and "as is" (reality) (Pramling et al., 2019). Three narratives have been constructed that exemplify how children's agency is supported in activities that integrate play and science. These narratives highlight how children's initiatives are given space to evolve and enrich both play and science; how children's initiatives become valuable for teachers' opportunities to "trigger" and further explore science content and; how teacher's constantly must respond to children's different initiatives and balance between them. Implications for preschool teachers and preschool practice are discussed in relation to children's agency in science teaching in preschool.