The photography lesson continues with histograms, explaining that a histogram is a graph of image brightness. Left side dark, right side bright. A histogram piled against the right edge indicates blown highlights, and against the left edge indicates crushed shadows. There is no perfect histogram; it depends on the subject. The lesson concludes with a challenge to photograph the same subject at different exposures and ask which best tells the story, and to remember to expose for the most important thing in the frame.