The first images are a warm light, cool shadow and a cool light, warmer shadow exercise. As part of the experience we were to take photo reference and use the colors and enhance the warm/cool aspects of them. I chose to take a photo of my beautiful wife Michelle. She's a great model and is always fun to paint. I've obviously exaggerated her proportions and stylized it a bit.
The second group is a study on different types of contrast: Value, Saturation, and Hue or color. We were to take the same drawing and paint it 3 different ways based off of the above criteria. The first is an image based on saturation. The second focuses value. The 3rd wasn't intended to look good. It was mostly to force us to keep everything the same value but create shapes with only color. Enjoy!