I like that though it would probably need to be somewhat interactive. Either that or you'd need a friend to do some of the call and response bits.

Probably most suitable if the audience includes lots of children.

You: "Hi everyone.

Today I'm going to be talking about some of the important concepts in science like falsifiability .... etc.

To help me I've brought John here and my Dragon."

John:"What dragon? I don't see any dragon."

You: "This dragon" [gesture at empty space] "I should probably have mentioned, he's invisible"

John: "... Ok, so he's invisible, lets see what his scales feel like" [wave hand through empty air]

And so on