4 Color Charts

We are more than half-way into our adventure in the Oil Painting Foundations at the Woodlands Art League. We've gone from a concentration on the study of values, with only one color + white, into a full but limited primary palette. We are using brown, blue, red and yellow +white.
At left is our last assignment: Color Charts.
Each set of color squares represents one of our colors and how it relates to every other color (rows) and how those mixtures look in a 5-point value scale (columns).
I brought this chart with me on my residency trip and could see why Richard Schmid is so enthusiastic about having these done and with you in the field. It's useful in note-taking in your sketchbook and my resident partner used it on the first full-moon night for her sketches, noting that she would have remembered a much higher key had she not had the actual color-values in her hand to refer to. And as just an exercise, every single square requires skill, discipline and much consideration. The OP-101 members made me so happy with their excitement and efforts. I have a completely different plan for our color safari tomorrow.