While there are numerous types of electronic learning environments including collaboratories, construction toolkits, systems with "scaffolding" and simulations, it is difficult to find authoring tools to build these systems. We have developed an application framework for constructing simulation-based learning environments called SimPLE (Simulated Processes in a Learning Environment). Environments developed with SimPLE use dynamic simulations and visualizations to represent realistic time-dependent behavior and are coupled with guidance material and other software aids that facilitate learning. The software architecture enables independent contributions from developers representing educational content (e.g., simulation models, guidance materials) and software development (e.g., user interface). We provide a user interface template and accompanying software aids to reduce the software development effort. (Also cross-referenced as UMIACS-TR-98-32)