A lot of English adjectives are built by adding - ed to a noun: grey-bearded, odd-shaped, simple-minded, pointed. The result means "havingI", so bearded people have beards, odd-shaped things have an odd shape, simple-minded people have simple minds and pointed remarks have a point.
These adjectives are worth some attention at key stage 3 because they're so efficient. The single word "grey-bearded" carries all the meaning of a "with" phrase ("with a grey beard") or even a whole relative clause ("who has a grey beard"). Just the job if you're trying to give the maximum of descriptive information in the minimum of words: "The leather-jacketed grammarian sat at his oak-panelled desk humming quietly to himself in a good-humoured way." There are three other reasons for exploring these adjectives: lConveniently, there's a negative equivalent of the "ed" suffix that means "not havingI". This is "less", as in "mindless", "shapeless", "pointless" and so on. You could even have "beardless" - but more on that below.
lTheir grammar is rather strange, because the noun often brings a modifier with it - "odd-shaped" is based on "odd shape" and "one-eyed" on "one eye".
Suffixes don't usually allow this. For example, "ful" has a rather similar meaning to "ed", so "successful" means "having success", but we can't say "great successful" to mean "having great success". Think of "ed" as a particularly broad-minded affix which isn't as fussy as most about the company it keeps - very useful for describing five-legged bug-eyed blue-bearded (whoops - we're getting carried away again) monsters at KS3.
lThere are interesting limits on the kinds of meanings that you can express in this way. We may be bearded, but we're not eyed or nosed or headed although we do in fact have eyes and noses and heads. This isn't because you can't add "ed" to these nouns - you can, but if you do it needs a modifier: one-eyed, red-nosed, long-headed. Why? Because everyone has eyes, noses and heads, but not everyone has one eye, a red nose or a long head.
And why is "bearded" so much more natural than "beardless"? Because not everyone has a beard. So you only deserve an "ed" adjective if its meaning is distinctive, if it picks you out from the crowd. This is a good way into talking about cultural stereotypes.
See what other examples they can think of, and then get them to invent some that might exist, but don't: great-rhythmed, many-goaled and, on the subject of flattery, good-teachered.
Richard Hudson is professor of linguistics at University College, London Geoff Barton is headteacher of King Edward VI School, Bury St Edmunds, Suffolk