Angela Duckworth was teaching math when she noticed something intriguing: The most successful students weren’t always the ones who displayed a natural aptitude; rather, they displayed something she came to think of as grit. Later, as a graduate student in psychology at the University of Pennsylvania, she defined the term — a combination of passion and perseverance for a singularly important goal — and created a tool to measure it: the “grit scale,” which predicted outcomes like who would graduate from West Point or win the National Spelling Bee. As a result of this work, Dr. Duckworth was named a MacArthur “genius” in 2013, and the notion of grit has become widely known. Her new book, “Grit: The Power of Passion and Perseverance,” will be available in May.

So why is grit so important?

My lab has found that this measure beats the pants off I.Q., SAT scores, physical fitness and a bazillion other measures to help us know in advance which individuals will be successful in some situations.

How does one develop grit?

You cannot will yourself to be interested in something you’re not interested in. But you can actively discover and deepen your interest. So once you’ve fostered an interest, then, and only then, can you do the kind of difficult, effortful and sometimes frustrating practice that truly makes you better. Another thing is really maintaining a sense of hope or resilience, even when there are setbacks.

How can parents foster grit in their children?

The parenting style that is good for grit is also the parenting style good for most other things: Be really, really demanding, and be very, very supportive. By this I don’t mean material things; I mean emotional support. If parents are warm and loving, the kids tend to feel loved. Respect, or what the parenting literature calls “autonomy support,” is also essential. That’s when parents allow their kids to make their own decisions just as soon as they are capable.