Garry's Mod (GMod) is a physics sandbox stuffed with art and models from Valve software's popular games, including "Half-Life 2" and "Counter-Strike." With a large library of generic objects, recognizable props from Valve's games, and pre-built devices like thrusters and wheels, users can build and share nearly anything they can imagine. Every object's physical properties can be modified, letting players tweak things like lighting or the amount of force and torque an object can create or withstand. With GMod, students can model solutions to physics problems, draw hypotheses about how things work in the real world, make films or sculptures, or just have madcap fun.
While the toolkit and physics engine are superb, GMod is nowhere near as easy to use as its spiritual cousin, Minecraft. If students don't already have experience with similar editing software, they'll need to spend a significant amount of time learning the ins and outs of the game's tools, materials, and settings. GMod also has some highly distracting assets –- weapons and scary, rag-doll character models -– which, like TNT in Minecraft, might derail more productive play. As a teaching tool, GMod benefits from focused use and clear expectations –- including what specific objects should be used. It's definitely a right kid, right time, right project teaching and learning tool, and unreasonable as a requirement for an entire class. But certain kids will fall in love and engineer fantastic creations.
Teachers can use GMod as a demonstration tool for physics experiments that are otherwise impractical for class. For example, a teacher could create a rocket, giant catapult, or two objects that push against each other with more force than can be safely (or possibly) generated at school. Teachers can also help students model experimental designs and solutions to physics and 3D geometry problems, and students who want to share their work (with the appropriate permissions) can work up and post expository pieces explaining their creations on DIY sites like Instructables. Teachers and students can also use GMod to create explorable 3D maps and models that connect to class content.