Could you post a survey asking the students what interests them?
It could be the first forum post maybe.
Maybe the students would like to discus
news, sports, movies, or music?
(or popular web 2.0 applications, social media,
bullying, books they are reading, pollution,
the environment,
global warming, world food crises,
plant based diet vs. high fat diet like paleo,
are you a cat lover or dog lover?)
Does your supervisor want it to be a grammar forum
where students can ask questions?
Here is a link to one student forum as a possible example:
There are some very good worksheets of high interest topics
for conversation that might be adapted
to a forum discussion.
http://eslprintables.com/buscador/
search.asp?nivel=any&age=0&tipo=
any&contents=pro+con&username=&B2=Search
http://www.eslprintables.com/buscador/search.asp?
nivel=any&age=0&tipo=any&contents=pros+
cons&username=&B2=Search
http://www.eslprintables.com/buscador/search.asp?
nivel=any&age=0&tipo=any&contents=
debate&username=&B2=Search
http://www.eslprintables.com/buscador/search.asp?
nivel=any&age=0&tipo=any&contents=
conversation&username=&B2=Search
