Zoho Discussions is a super simple way to create “chatboards” that would work well for “sister classes.” There are a lot of alternatives, including ones that have the ability for users to participate in a chatboard by leaving audio messages.
Since Zoho’s is just so easy to use, though, I’m still adding it to The Best Online Tools For Collaboration — NOT In Real Time.

September 22, 2009 at 6:19 pm
Hi larry, try checking out voicethread.com too. I use this to communicate with parents but it should work well too with your students.
September 22, 2009 at 7:35 pm
I’m starting to explore Zoho quite a bit, hoping to use it as an alternative to Google. I like what I’m finding and will explore the Zoho Discussions possibilities. Thanks for the information.
September 24, 2009 at 8:15 am
I hadn’t thought of using blogs for teaching situations but communicating with parents and having on-going conversations that way is most interesting.