Pedagogical tools are designed to convey important lessons and allow people to improve their understanding of a problem or undertaking. Though in a sense, these are the goals of any successful system dynamics study, the pedagogical tools focus on the teaching part, not the analysis of novel situations.
Silico from silicoai.com is a browser-based system dynamics modeling tool. Key features include real-world value-comparisons and time-charts on every item, and time-zoom, making model validation simple, plus slick scenario-testing and model-sharing. Silico is super-easy to use (see its user-guide videos), so is ideal for teaching. The fully-functional Community edition is free, as is its use in education.
InsightMaker®, from Give Team, is a powerful, free System Dynamics modeling tool that runs completely in the browser. It enables you to build, run, and share System Dynamics models without downloading or installing a single program.
NetLogo®, from Northwestern University, is a multi-agent programmable modeling environment. It has the ability to build system dynamics models. It is used by tens of thousands of students, teachers, and researchers worldwide. It also powers HubNet participatory simulations.
Stella, from isee systems.
VisualAivika 5®, from Aivika Soft, is an easy-to-use diagram editor that allows creating nice-looking Casual Loop Diagrams (CLD) as well as Stock and Flow Maps (SFM). There is also a simulation component that supports its own high-level modeling language. There is the equation editor, where you can define integrals, arrays, random functions. Moreover, VisualAivika supports the Monte-Carlo simulation, which allows providing Sensitivity Analysis. There are means for plotting charts on the diagram to show the results of simulation in a form of Time Series, XY Chart, and Deviation Chart. The results can be exported.