Disclaimer - I'm not early years!
That sounds lovely. Initially I thought all on a big carpet but if you have a smaller one the other children could ask questions about what the ones on the carpet can see. This might keep them under control a little bit and give more chance for them to do the thinking and share their ideas with the class.
Not sure what they'd ask apart from, "what an you see?" though!
Or maybe if you have them all on the carpet, they could, think, pair, share and feed back to you what they saw as a class. Or they could think, then discuss it with their partner, practise what animals they imagine and act out the animal for the class.
15 minutes is tight though and I'd worry that by the time you've explained everything your time might be up.
If they're really just looking at how you interact, might it be simpler to read a book and get them to act out each scene. Where the wild things are springs to mind. Yo could read once, get them to pretend to be naughty max, then going over the ocean, then be the monsters, have the rumpus with some music playing.
It would give a clear structure to your input, manages the pace nicely, shows you're imaginative but you can also show off your behaviour management rounding them up for the next scene. Give out stickers for use of really descriptive words when they describe what they're doing. That also would show off your questioning technique. And if time runs away a bit you can skip scenes but still get your lesson point across.