This document discusses 3D multiuser virtual environments (MUVEs) for educational purposes. It defines MUVEs as networked virtual reality spaces where users interact through avatars in 3D simulated spaces. MUVEs have features like avatars for user representation and interaction, shared virtual spaces for collaboration, and interactions between users and virtual objects. The document outlines pedagogical approaches used in MUVEs like constructivism, active learning, and collaborative learning. It also discusses opportunities and challenges of using MUVEs for education, and questions for future research around student engagement, motivation, and designing learning tasks in virtual environments.