Pupils are given picture prompts with optional vocabulary on the reverse of the pictures. Those who need to can refer to the vocabulary during the task. Using the group talk structures, they are encouraged to have spontaneous conversations.
Group talk can be differentiated to allow all abilities to participate.
I normally use groups of 4 or 6 and set a time limit. Afterwards, I encourage reflective feedback and ask for examples of conversations.
I also use peer assessment sheets so that pupils can assess each other.