Chatter mats are great for getting students talking to you and other staff but also for talking to each other. The ones available on the TES are made by Sam Maxwell and use Widget symbols to prompt students and provide them with a reference point for conversation.
I have since made loads using Communicate in Print, I made one recently for a P.S.H.E. lesson where students were making smoothies for each other, it had a bank of fruit symbols we were using and 3 questions down the side to prompt students in what to say to each other. They work really well for students that have difficulty in word finding!
(widgit symbol software: Communicate in Print)
I will try and add some photographs of some of my chatter mats as examples but check out Sam Maxwells on the TES