To supplement my classes, I have been putting together a series of educational interactives in javascript. You are welcome to use them for educational purposes.
Interactives have been tested in Google Chrome and most have been tested in Firefox, and they may not work or appear correctly in other browsers, particularly Internet Explorer, or on devices with small screens such as phones.
Sage Math Cell (Modified BSD license). Information about calling SageMathCell servers directly can be found here (replace http:// with https:// to avoid a CORS error).