Drawing course week #1 and #2

During the first two weeks of Basic Drawing course, I have learned how to do a few different types of contouring. Among them, the first was continuous contouring, drawing without stopping between starting and finish line. This following image shows how you draw the continuous contouring lines. 

The second was weighted contouring. The most important concept of contouring is that you do not shade or express volumes. You can express weight by the thickness of lines or making cross sections like following images:

these two apples simply have same shape but different in the thickness of the lines. The apple in the right, however, seems to have more weight than the left because of the thicker, bold lines at the edge.

Meanwhile, weight can be expressed simply by the cross contouring lines. It means drawing many cross lines through your main object drawing. Weight can be expressed by many cross lines through the main object like the image above.