The value scale is a diagram of ten values, ranging from white to black. White is the first step, and is number one. Black is the last step, and is number ten. In a value scale, those steps from white to black are equally spaced and are numbered 1 through 10.
Value scales are helpful, because we can describe a very dark color or value by calling it a number. A very dark color could be an 8, 9 or 10. We can describe a very light color by describing it as a 1, 2 or 3. If we want to describe the values that are in between black and white, the middle values, we would use a 4, 5 or 6.