Training practical skills from a book with a teacher lecturing on a subject cannot replace the experience of actually applying those skills. Virtual worlds allow easy simulations of fire drills in hospitals, mob/riot control, or the steps required to enter a clean room on a high-tech industry plant. Items are faithfully recreated and instead of reciting checklists by heart or role-playing in class, trainees can actually “enter” the virtual simulation and interact with it — and with colleagues and trainers — to understand how to react in the real world.