I am planning on holding a workshop later this spring teaching how to mix blacks. I am using a lesson plan created by Char McGill (http://www.charmingart.org/) (we exchange lesson plans) but I need to paint the demo paintings to make them my own and have the paintings there as an example. The fun way to teach blacks is with zebras. The first painting of the single zebra is based on Char's lesson. The second will be a slightly different approach. I also am doing them on watercolour paper wrapped around a canvas and they will then be varnished.
The first painting is finished (above) and I'll show the steps in the second one. Here is step 1 - adding shading in the beginning.