As additional practice, and a homework assignment, I assigned the eighth graders what I call a Value Study Project. The assignment had specific directions that they could each interpret in their own way. For example: Draw 4 lines that start and end at the edge of the paper, add one line that looks like waves, add two lines that looks like lightning. After the lines were drawn, the student needed to color the shapes they had created using the different shading techniques we learned in class (gradation, pointillism, and cross-hatching).
Here are some of their finished products: