Dynamic web-based learning tools are indispensable in modern teaching, especially considering their capability for interaction on demand as a means of stimulating and engaging students. The experience on which the results reported here are based has grown out of progressive testing of different approaches for publishing technical sketches and mathematical notations from the field of electromagnetics on the web, starting in 1997 with simple static web pages of solved examples. The encouraging results from using and evaluating this educational material and the needs expressed by students for learning from more dynamic and interactive web learning materials that offer the possibility of changing parameters in online calculations motivated a search for new approaches to publishing interactive learning materials on the web. Integration of already developed components for building animations, presenting mathematical equations, and performing online computations with browser scripting led to development of a learning environment where animations are synchronized with corresponding derivations of equations and supported by dynamic, parametric-driven calculations and visualizations that can be integrated with sound and video. The system supports tests and examinations in which the answers are provided as mathematical notations. The use of Mathematical Markup Language (MathML) permits equations in the learning materials to be copied and pasted into most of the popular mathematical software tools for algebraic manipulation or numerical computation. Examples demonstrate how the system can be used with a course on electromagnetics, although the basic approach is applicable in other fields of engineering and natural science.