What makes a composition simple? Few shapes? Enough overlap to locate the shapes in space, but not so much to complicate the relative distance? What else?
Mr. Wyeth, again. This sketch looks like a composition study. The land forms are few, the overlap minimal. The artist has placed objects as if to see whether this layout enhances or limits the illusion of space. Wyeth likes to create a tenuous balance, often stretching the placement of the shapes to the point of tension.
Why do you think Wyeth placed that gate so that it is surrounded by light? What if this were a horizontal composition? Is this a simple or a complex composition? That's a lot of foreground considering how little specific information it carries. How many artists sitting on this hill would have cropped one side of the pond off? I suspect most of us would have made sure the whole pond was in the scene first thing. The big, simple shapes seem quite abstract. Isn't this really more abstract than representational?
For homework, have some fun rearranging the compositional elements of one or more of these, or choose an image of your own. Anything goes!