I had my first and second graders draw and paint "imaginary creatures"
like four-headed dragons and giant bird-like things. Each one had to contribute
to the idea and do a part of the whole drawing. They had to decide about
things like scales and feathers, feet, wings heads, colors, etc. and make up a
story about it. They had lots of fun and some of the results were really neat
looking. With older kids you could look at Gorgons and Sphinxes and all kinds
of mythical beast as an introduction.