The use of head mounted displays (HMDs) to experience virtual realities (VR) has become increasingly common. As this technology becomes more affordable, immersive and easier to use, it also becomes more serviceable in educational and training contexts. Even though the technology, content and feasibility for K-12 school purposes are still being developed, it is reasonable to expect that the call or 'push' to use HMD VR in K-12 schools will increase, especially as there is now a greater economic interest in the use of digital technologies in educational contexts. This article aims to inform the process of implementing HMD VR in K-12 contexts by researching the preconditions and challenges of use from a teacher perspective. It does this by analysing the organisational, institutional, contextual and practical challenges and opportunities in the implementation of HMD VR in K-12 school contexts. The data draws on (a) interviews, informal conversations and observations of teachers testing HMD VR and different VR applications in a Digital Learning Lab (DLL) and (b) data from a project involving upper secondary school history teachers discussing the planned implementation of HMD VR in their teaching and being in the DLL. The main findings are related to: (a) economy and technology, (b) initial learning barriers, (c) organisation and practical enactment for teaching and learning, (d) curricula, syllabuses and expected learning outcomes and (e) teachers' competences, professional development and trust. The consequences for educational contexts and possible ways forward are also discussed.