Abstract: A tool-workpiece instructional system is provided for simulating operation on a workpiece in the form of a welding site as shown on a display, by a student using a tool such as a welding torch simulator. The torch is a mock-up of as real torch, having mock values and torch tip, but is not supplied with any gas. A light pen and mercury switches are mounted inside to detect torch position and angular position relative to the display. A computer with a control program uses information regarding parameters of torch location relative to the display, including torch angle, torch distance to the display, torch position as projected on the plane of the display, welding rod position (as detected by a touch screen on top of the display) and oxygen and acetylene valve positions of the welding torch, and uses the parameters to determine what would happen to a welding site during a real weld and addresses appropriate segments in a video disc player to display a simulation of the welding site in real time.