Mass adoption of virtual world platforms for education and training implies efficient management of computational resources. In Second Life Grid and OpenSimulator, commonly used for this purpose, a key resource is the number of servers required to support educational spaces. Educational activities can take place at different altitudes over the same virtual land, for different classes. This way a single virtual world server can sustain several different educational spaces/classes, reducing the number of servers needed to make available different classrooms or other educational spaces. One issue whose importance is emphasized in such conditions is that of class privacy, bearing in mind that most privacy-management features of these platforms are land-based, not space-based. In this paper, we provide an overview of the issues to consider when planning privacy in these platforms and the methodologies that can be developed and implemented to ensure it at an adequate level, including the extra privacy possible in OpenSimulator regarding Second Life Grid.