The point was so obvious, it was almost embarrassing. Kids stared at their teachers for hundreds of hours a year, which might explain their expertise. Their survey answers, it turned out, were more reliable than any other known measure of teacher performance—­including classroom observations and student test-score growth. All of which raised an uncomfortable new question: Should teachers be paid, trained, or dismissed based in part on what children say about them?

Kail’s experience is instructive. As soon as she began teaching her students the Greek and Latin origins of many English terms — that the root sta means “put in place or stand,” for example, and that cess means “to move or withdraw” — they eagerly began identifying familiar words that incorporated the roots, like statue and recess. Her three classes competed against one another to come up with the longest list of words derived from the roots they were learning. Kail’s students started using these terms in their writing, and many of them told her that their study of word roots helped them answer questions on the SAT and on Ohio’s state graduation exam. (Research confirms that instruction in word roots allows students to learn new vocabulary and figure out the meaning of words in context more easily.) For her part, Kail reports that she no longer sees rote memorization as “inherently evil.” Although committing the word roots to memory was a necessary first step, she notes, “the key was taking that old-school method and encouraging students to use their knowledge to practice higher-level thinking skills.”

. A study published in the Journal of Research in Science Teaching in 2010, for example, found that 10th-graders who were taught how to construct an argument as part of their lessons on genetics not only had better arguments but also demonstrated a better understanding of the material

If you ask students what are the most important qualities they like in teachers, one of the universally top-mentioned is fairness. Teachers and schools strive to be fair and build programs and polices based on this value.