Something I've just thought of is taking a sample of words that have undergone a lot of semantic change. So, all the bread-and-butter names for woman and difference like 'silly' meaning blessed and then young. You could have them act out small roles where they get to call each other all sorts of stupid names (but in a serious sense). You would have people addressing people as "Lord", but get them to say the etymological sense, "the one who guards the loaves". It'd be really stupid and funny, but informative. They'd probably have a bit of a laugh but definitely walk away with some deep realisation that so many things in English are obviously changing. Having retirees refer to each other as 'wench' when the script needs to address a small, female character. You could easy get a good range of 20 words and put something simple together. Having it a bit silly, tongue-in-cheek, but still bringing that look of, "Did it really use to mean that? I never knew." My experience is that older people love etymological facts and as long as you have the basic process of how these words changed and the system of amelioration or pejoration as an explanation, it could turn out to be fun for them.
So you could work with words such as lord, wench, knight (boy), bastard (illegitimate/not pure) etc. There's always the reference to "William the Bastard", which was never meant as an insult. You could play on it with characters asking them to pass the "bastard cheese" or something, cheese that's not quite pure or whatever. I'd actually like to see a bunch of people doing an activity like that.
