This article provides the first review of the existing literature consolidating research into the use of virtual, augmented and mixed reality technologies within K-12 educational environments. The review explores the peer-reviewed scholarly studies conducted between 2006 and May 2017, which involved the use of virtual reality (VR), augmented reality (AR) or mixed reality (MR) technologies in the instruction of students in elementary, middle or high school. The literature revealed common themes including collaboration, communication, critical thinking, attitude, engagement, learning, motivation, performance or achievement, and technology (used or proposed). This literature review will contribute to the field by providing clarity on definitions for VR, AR and MR technologies in consideration of educational use, present an overview of the existing research on VR, AR and MR specific to K-12 educational environments and identify future research needs and directions.