What to do:
In order to increase oracy levels of students and get them answering questions as productively as possible, try this…
I would like to add to the point X has just made or, I am challenging what X has said, because… or, to build on what X has stated would need…
Use, Try, Refine, Ditch with students too?
Get students to stand up to answer questions, only one person can speak/stand at a time, makes controlling a discussion much easier?