Start by identifying the major shapes in the image. There should be no more that 10 or 12.
Make a simple drawing that locates the shapes.
Paint in the first layer - the lights - of each shape, keeping the treatment as simple as possible (no texture or detail).
Now make two more first layer pages, so that you have 3 more or less identical sheets.
Put the second layer - middle value - on top of the first on two of your 3 sheets.
Finally, apply the 3rd layer - the darks - on top of one of the second layers.
When the process is finished, you should have one sheet that just has the first layer, one that has first and second layers, and one that has three layers. Please bring all three, plus the photo in to class.
In case you missed class, here are a couple of simple images that will resolve nicely into three layers. If you think there should be a fourth layer of super darks, put them on top of the three layer treatment.