I've never taught that age group, but I bet they could learn to make
wire spirals. When you've never worked with wire, they look so
difficult and mysterious--and when people learn to make them, they
tend to feel like real insiders. Spirals can also be hammered, which
is always a big hit (so to speak). I have a cardboard chart to which
I have taped spirals--hammered heavily, lightly, and not at all, as
well as "closed" (easiest to make) and more open--indicating the
various gauges and lengths of wire used for each.
I've noticed that many people who teach absolute beginners how to
make earrings begin with head pins and "perfect loops." It's a rare
beginner of any age who can actually make perfect ones, and this can
lead to frustration (even if you have lots of time, some people will
get bored before they get proficient). One way around this is to use
finer wire and teach wrapped loops, which are somewhat easier. But
you then have other problems, e.g. needing to work with long head
pins--usually more expensive.
However, if you teach spirals, you can use standard sterling eye
pins, with a "perfect loop" already in place. Once they've practiced
the spirals (I would start with copper, then use silver "scrap"),
they can thread beads onto the eye pins and spiral the ends, to make
"custom" head pins. Then you can teach them the proper way to open
and close the loop on ear wires--you might want to bring a bunch of
jump rings, too. That's a little trick that will serve them well
throughout their lives; even if they never make jewelry again,
they'll know how to do the most basic repair.
Once they feel comfortable with pliers and wires, and have
successfully made some earrings, you could show them how to make
perfect and wrapped loops, jump rings, etc. Then they can design
their own necklaces and bracelets. You might want to bring along a
couple of wire jewelry instruction books, e.g.