It is well established that schools are not neutral sites for gender and sexualities, shaping (often heteronormative) school spaces. This paper augments examinations of the implementation of inclusive school curricula by exploring heteroactivist opposition to lesbian, gay, bisexual and trans (LGBT) equalities in Canadian and British schools. It examines resistances to institution of a revised and updated Health and Physical Education curriculum in Ontario schools in Canada, and in the UK, the use of the Rowe family’s opposition to the presence of trans children in their own child’s classroom. This paper shows that once-invisible heternormativities are now being challenged through LGBT curricula and support for trans students. This creates classrooms as pivotal, geographical, social and political spaces that operate at the juncture of the public/private spaces of the home, public spaces of the neighbourhood and the imagined space of the nation and nation-building citizenship. Oppositional ideologies can no longer be understood through the labels of ‘anti-gay’, ‘homophobic’ or ‘transphobic’, and these oppositions go beyond ‘anti-gender’, such that the term heteroactivism names the activisms and ideologies that seeks to reassert the superiority of monogamous, binary cis-gendered, coupled marriages as best for children and for society. These ideologies are inherently geographical, drawing both on local and individual circumstances, but also transcending national boundaries. We highlight three dominant heteroactivist themes, namely, parental rights, interactions between state/schools/home and gender ideologies. This offers insights into how new sexual and gender rights are contested and resisted in new ways to consider the political, legal and social implications of heteroactivist strategies in schools.