For the age group you are talking about, I suggest having them draw a scale,
the kind of grocery store scale that has two sides. Then draw a great big
square on one side, sitting on the scale, and several small squares on the
other side. That's balance. Now you can distribute those squares on a
blank sheet of paper. Either re-draw them, or cut them out and paste them
You could do the same exercise with a large black circle and a small red
circle. Show how a small bright object can balance a larger darker object.
Then show how a newspaper page is designed and balanced, between text and
If you had more time, I would say draw the balance scale on a piece of
paper and xerox it for them, as a starting point for their exercise.
Other possibilities: a felt board with geometric shapes of varied color and
size, which you can have them arrange in a balanced composition.