This document discusses using 3D simulations and virtual reality to bring real world experiences to online learning. It argues that simulations allow students to "do" and learn through situated, immersive experiences. Game engines now provide opportunities to create engaging learning environments that capture real world concepts and allow students to apply knowledge. Examples of existing simulations are provided in various fields like healthcare, sciences, and engineering. The document envisions a future where simulations are more fully integrated into online education through virtual campuses and environments to improve learning outcomes.