A lesson that is always successful is large flowers outlined with black
glue. You can make the black glue by mixing with black tempera or black ink
(experiment with a small amount - sometimes them chemical make-up doesn't
work with some brands of paint). Flowers are drawn large to fill the
page -- outlined with glue. Then water color pencils are used (after the
glue dries)- blending colors (good lesson for analogous /related colors).
Regular watercolors can be used for negative spaces and over the water
color pencils. Negative spaces could be painted in complimentary colors -
complimentary to the colors used for the flowers. The black glue also
works well with soft pastels and oil pastel drawings. If you do not want to
make black glue, you could use regular Elmer's on black paper - then do the
pastel drawings. The glue will dry clear - creating a black outline.