1.  Swamp pupils with a variety of poetry anthologies or poetry sheets.  
You can choose to select the poems on a theme ( eg MONSTERS / NATURE ) 
or allow for a diversity of topic.
Encourage general reading and sharing, a getting into the texts for 
enjoyment, some readings tend to arise naturally from this process.
Have numerous strips of paper available and ask pupils to pick out lines 
which they have found to be descriptive,interesting, or unusual.  Give 
your own as examples.  Talk a little about the language and imagery.
Ask for 10 to be written on the strips of paper, folded, and submitted 
to a common box.
Once done, mix up and share out.  Ask pupils to lay out strips of paper 
and to look for lines which seem to develop a theme.  They can discard 
lines, swap lines, and of course write their own.  
Begin a drafting process where they develop the ideas they have, 
encourage changing the gender,making subject and verbs agree and so on.  
The result is a hive of activity and creative intent.  
Usually short ( 6 - 10 lines ) poems are created which read as enigmatic 
statements.  They are usually full of imagery and lend themselves to 
illustration.
 
2. Having studied figures of speech, and metaphor in particular, use a 
similar process but have the pupils write their own descriptive lines.  
This may be on a theme given to them or left to up to individuals.  A 
theme usually helps less mature pupils to focus.  Follow the same 
process.  Use the results to illustrate the power of metaphor.

 
Never failed me yet.  Great fun.
 
John McKellar.  Darlington, Co. Durham. England.