I think yours is a great idea for a 5-minute demo lesson. I'm sure others will have more exhaustive comments, but a few things come to mind:
-CELTA teachers are big on "eliciting" words and getting students to talk. "Eliciting" often means giving hints until someone in the class guesses the word. In your demo, it wouldn't hurt to engage the audience in some way. For example, instead of giving a monologue while introducing yourself, walk in and say "HELLO". If you have a cooperative audience, they will respond, if not repeat "HELLO!" and motion for them to answer in kind. Continue accordingly, with "i am from, " "my name is", and that may be enough, as this will take up 2 minutes or so. Remember that you can't speak too slow.
-Instead of simply handing out a list, try to get the students themseves to come up with alternatives, or at least one of the words. For example you can hold your bladder and say "where do i need to go" or similar. Someone might say "toilet". You give them the thumbs up or whatever (the point is for them to talk, not you). You can write it on the board, have and next to it write "loo". Then encourage, in oversimplified language, students to decide which word comes from where.
This is quite a task they're setting you, as it is assumed CELTA candidates know zero about teaching. Not quite fair in my opinion, but you'll certainly learn a lot. Good luck!
- For Teachers