What color is black?

What your teacher said is not accurate enough. Theoretically, pure white and pure black have no color tendency, but usually the temperature of color is relative. You can tell whether some colors are cold or warm as soon as you take them out, but in the face of colder or warmer colors than him, his color tendency is the opposite. Under normal circumstances, we seldom really use pure white or pure black when painting, because the existence of everything will be affected by the surrounding things or environment, and the color will also be affected, so white and black will show different cold and warm tendencies in different environments, which can only be aimed at specific situations and is not certain. In other words, black and white can be cool or warm, depending on the overall tonality of the picture and the surrounding environment.