In this study, we investigate the phenomenon of Swedish Natural Science sexuality education. These classes tend to provide factual knowledge, focus on the negative outcomes of sexuality, be heteronormative and include little time for discussion--like much school sexuality education across the world--and this study aims to contribute ideas about new becomings of Natural Science sexuality education. Baradian theorising was used to explore how materialities and space and time travels within the classroom can challenge often-dominant perspectives. Data were produced in a secondary school and consist of teacher-researcher discussions and participatory observations in class. A futuristic case introduced students to spaces, times and materialities that not only helped the group move beyond a medical focus but also made the sexuality education more student centred. The participating teachers suggested imaginary lust-oriented scenarios for the 15-16-year-old students as an entrance to more preventive messages in teaching. A taken-for-granted heterosexual premise was also challenged with gender-neutral words and pronouns, an exercise on how to use both condoms and dental dams, and a time travel into future possibilities for reproduction and parenting. The acknowledgement of spacetimematter intra-activity in teaching thereby enabled new becomings of Swedish Natural Science sexuality education. However, although this study suggests how dominant medical and heterosexual perspectives can be challenged, it also made visible the absence of cultural, religious, asexuality and disability perspectives in Swedish sexuality education.