What's "marshall's class"? anyhow the comp studies are amazing...makes me wanna do some! XD
I'm taking "Composition and Color I" from Marshall Vandruff at The Art Department, he's an amazing teacher. You should definitely do some. I just open up two canvases side by side and use my eye to get the shapes and colors, the less tricks you use like eye-droppers, etc, the more you will get out of it. Thanks.