A discussion in class will be more effective if the topic is

Informing students of the topic in advance lets them prepare, so the discussion becomes richer and more effective.

Not introducing the topic at all leaves participants unprepared and aimless.

Stating it only at the start of the discussion gives no time to gather ideas.

Writing it on the board without introducing it offers no real preparation.

Prior preparation is a precondition for a productive group discussion.

A well-briefed group discussion develops thinking and communication skills.