Pyramid discussions often involve the whole class at the end.
Example
In small groups, the learners have to agree on the most important of the five senses. They then join with another group and have to agree again, and so on, until the whole class is involved in one discussion.
In the classroom
Pyramid discussions are useful for practising a range of functions, including agreeing and disagreeing, negotiating, summarising, and putting forward an argument.
Further links:
https://www.teachingenglish.org.uk/blogs/davidinberlin/why-you-should-use-fewer-materials-class
https://www.teachingenglish.org.uk/blogs/cerirhiannon/ceri-jones-just-say
https://www.teachingenglish.org.uk/blogs/david-petrie/david-petrie-space-spontaneity