Open class work is often teacher-led.
Example
The class have finished analysing a text on inventions and in groups have looked at discussion questions based on the topic. Their ideas are now fed back to the whole group in open class.
In the classroom
Teachers have to make decisions about whether to do an activity in closed groups or open class, or a mixture. It can be difficult to ensure that all learners are involved in open class activities as the more confident can dominate.
See also:
https://www.teachingenglish.org.uk/article/closed-pairs
https://www.teachingenglish.org.uk/article/open-pairs
Further links:
https://www.teachingenglish.org.uk/article/group-work-v-whole-class-activities