The discussion method is useful if

The discussion method can be useful in all kinds of situations, because a skilled teacher adapts it to varied topics and aims.

It suits clarifying easy ideas, unpacking difficult ones and probing complex or debatable questions alike.

Saying it works only when the topic is very easy is too narrow, since discussion also deepens hard content.

Saying it works only when the topic is difficult ignores its value for reinforcing simpler material.

Saying it works only when the topic is very difficult wrongly limits a flexible, general purpose method.

Discussion rests on two way communication and shared inquiry, which is why its scope is broad.