What? "on a blackboard"?? If KhanAcademy doesn't have any, I don't know of any other sites.
The first two to five links in any search results are usually the very best ones. I'd start out with Wikipedia in each one, not only because the articles are good, but also because each article has further references and external links at the end.
You could also re-search these topics at http://scholar.google.com
I'm not sure about sites for speaking and listening. I've checked out these, but I don't think they have what you want:
You could work on contacting someone at each of those sites and seeing if they know of a ways to do this.
Also, you might ask your school (maybe someone in the library?) about setting up something like this with a "sister school" in the US or England.