A computer-based educational system provides the user or instructor with a suite of graphic editing tools, allowing the design of graphical objects, such as symbols and text that can be displayed to a viewer, such as a student, using a projector or computer terminal. In order to facilitate the educational process, the invention provides the user with robust ability to control parameters of the graphical objects, allowing the user to create simulations or models of subject matter, such as mathematical principles, in order to facilitate the educational process. In the preferred embodiment, the parameters of these graphical objects can actually be defined in terms of variables and specifically functions or expressions including those variables and then the values of the variables controlled in real-time by the user. This ability allows the user to control the execution of the simulations or models, enabling the user or instructor to dovetail the execution of those simulations with the instructional process.