“It ain’t what you don’t know that gets you into trouble,” said Mark Twain. “It’s what you know for sure that just ain’t so.”
Teachers need to know the wrong answers to teach the right answers, says Philip Sadler, a professor of astronomy who runs Harvard’s Science Education department. It’s hard for teachers to explain concepts unless they “understand the flaws in students’ reasoning,” writes Anya Kamenetz on NPR.
It takes a lot of “mental effort to change the ideas that you come up with yourself,” says Sadler. “It’s a big investment to say, ‘I’m going to abandon this thing that I came up with that makes sense to me and believe what the book or the teacher says instead.’ ”
Sadler gave a multiple-choice science test to middle-school students, including a “distractor” — a common misconception — for each question, he writes in American Educator.
2. Eric is watching a burning candle very carefully. After all of the candle has burned, he wonders what happened to the wax. He has a number of ideas; which one do you agree with most?
a. The candle wax has turned into invisible gases.
d. All of the wax has melted and dripped to the bottom of the candle holder.
Fifty-nine percent of students chose “d.” Only 17 percent chose the right answer, “a.”
When Sadler tested the students’ teachers, they knew 85 percent of the right answers, but only 41 percent of the “right” wrong answers, writes Kamenetz. Students whose teachers were more aware of common errors “learned significantly more science, based on a retest at the end of the year.”