The recent discussion started by fface on the English Questions Forum
regarding expressions like at large, fair game, on the loose,
and on the run
reminded me of an article I wrote for An ELT notebook
about six months ago : My Teacher is an Old Cow - Teaching figurative language, should we or shouldn't we?
If you have been following the discussion, or if you want to find some links to activities teaching figurative language even at lower levels, you might like to check it out.