For each composition, I used Adobe Illustrator to make and manipulate 9 squares (each 72 pixels, or 1 inch).  The squares were able to touch, but not to overlap. 
For the first composition, I created a foreground, middleground, and background by positioning the blocks into three columns, containing 2, 3, or 4 blocks. The longest column extended below and above the other two, and the middle column below and above the smallest. This creates the illusion of distance.
The second composition showed a figure/ground relationship. By having a negative shape (white space) inside the black figure, the eye can focus on either shape.
The third composition demonstrated the concept of similarity by depicting two shapes that are almost, but not completely identical.  The second cross has an additional block on the top arm. 
The fourth composition illustrated the principal of proximity.  When shapes are closer together, they seem to be in a group, and a shape farther away will not be seen as part of that group.
The fifth composition depicted closure, by creating a shape that is not fully completed or closed, but gives the illusion of completeness. In my image, I created a rectangle with several open spaces that the eye/brain closes to create the shape.
The sixth composition showed continuation by making the eye move along a curve. I created a backwards “S” by placing the blocks in a series of staircase-like rows.
The final composition in this assignment demonstrated symmetry. I created a torso with vertical reflective symmetry and a central square representing the heart.