why do art history professors go “ you need to answer to this questions about an artwork of your choosing from your textbook, each answer needs to be 5 to 8 sentences long”

first question: what was the purpose of the artwork?

what the textbook says about the artwork: “ depict the October 1867 signing of peace treaties between the Cheyenne, Arapaho, Kiowa, and Comanche peoples, and the United States government, at Medicine Lodge Creek, a tributary of the Arkansas River, in Kansas.”…

as far as I know, that’s not 5 to 8 sentences not even if I put it in my own words unless the professor wants me to just ramble on it and repeat those what 2 sentences or so….