Given this is supposed to 'introduce the genre', I'd think I'd start simple and general if talking about rules, mentioning examples towards the end.
However, I should think the real beginning is showing people the origins, Victorian 'rippin' yarns' and the stories of Empire.
Then, move to the introduction of science fiction, including the fiction of Wells and Verne, the films of Melies, perhaps mentioning some particular experiences. You know I'd be including James Mason on the Nautilus. ;->=
But we don't want to just read or placidly watch, we want to act, and to share the action. I'm not sure but you might want to mention the 'in person' aspect versus on line. Justifying toy soldiers and their 'toy conveyances' is a constant battle.
Too much?
Doug