Among many topics covered during the first lesson is a segment about styles and types of fabrics, and characteristics of design: scale, contrast, and value.
Value is often an elusive concept to grasp. Even when showing the quilt top (below) that was specifically made to explain the attributes of various prints, value can be difficult to see. To show it more clearly, it's helpful to photograph your fabrics or quilt top. Then compare the color version to a black and white version. Value becomes very apparent!
The fourth row of tone-on-tone print loaves (3-1/2" X 6-1/2" unfinished rectangles) clearly shows that these loaves are not in value order! They're not lined up from lightest to darkest. Interesting, isn't it?
Hopefully this demonstration will help you understand value, and how it makes your quilt more interesting when you select fabrics with a variety of light, medium and dark values.