The students and I discussed the lines we saw in images of Birch trees. They compared the texture and color of Birch tree bark with that of other trees.

We had a discussion about how an artist can add interest and uniqueness to their artwork by changing things from how they look in "real life." I introduced the term "Artistic License" to them and told them they each had one to be creative with. I encouraged them to add other colors into the bark of their birch trees if they wish to do so. Many used different colors of oil pastels to blend into the white and black of their trees.
The last step in the project was to use primary colors of watercolor to paint in the background. We were reviewing how the primary colors mix to make secondary colors, so I encouraged them to mix them together as much as they wanted to.
This is one of my favorites! See more student works in our Artsonia gallery - http://www.artsonia.com/museum/gallery.asp?exhibit=561263