Ow can Play develop independent learning for Reception children

I am volunteering in a Reception class as TA and the topic this term is Tell me a story”. We are reading tales in the whole classroom and then Im gathering 6 children to do play activities according to the tale we have read that day. I work mostly with observation but where it is needed I participate with them in the play to give directions. I have 6 children for half an hour per day. I work 2 days per week, so an hour per week. The assessment should be based in observation but also research. How can play impact in communication skills and speaking? What is independent play/learning?