Create three lists of words:
(a) words that are no longer used
(b) slang used within their own peer groups that probably are not known to outsiders.
(c) a list of words referring to the same referent (for example, someone’s friend may be referred to in many different ways, such as pal, buddy, companion, soul mate, partner).
After you compile your list, talk about the the arbitrary nature of symbols and why perfect understanding is not possible. For your words, please define them so we can understand what they mean.