Elissa Nadworny

Our Take A Number series is exploring problems around the world, and people solving them, through the lens of a single number.

Ron Ferguson, an economist at Harvard, has made a career out of studying the achievement gap — the well-documented learning gap that exists between kids of different races and socioeconomic statuses.

But even he was surprised to discover that gap visible with "stark differences" by just age 2, meaning "kids aren't halfway to kindergarten and they're already well behind their peers."

A federal judge ruled this week that Education Secretary Betsy DeVos' delay of a key student borrower protection rule was improper and unlawful.

"This is such an important win for student borrowers and anyone who cares about a government that operates under the rule of law," says Toby Merrill, of Harvard Law School's Project On Predatory Student Lending. The judge is expected to order a remedy in the next week.

Sylvia Acevedo grew up on a dirt road in New Mexico. Her family was poor, living "paycheck to paycheck."

After a meningitis outbreak in her Las Cruces neighborhood nearly killed her younger sister, her mother moved the family to a different neighborhood. At her new school, young Acevedo knew no one. Until a classmate convinced her to become a Brownie Girl Scout.

And from that moment, she says, her life took on a new path.

On one camping trip, Acevedo's troop leader saw her looking up at the stars.

Popular culture tells us that college "kids" are recent high school graduates, living on campus, taking art history, drinking too much on weekends, and (hopefully) graduating four years later.

The U.S. Education Department is proposing changes to Obama-era rules that offer debt relief for students who were defrauded by their colleges.

Look people in the eye. Smile. Shake hands. Sit up tall. Speak clearly and confidently.

That's the last-minute advice professor Paul Calhoun gives a handful of college students before they head off for a series of job interviews. The Skidmore College juniors and seniors he's talking to are dressed in suits and button-downs; dresses and heels. They stand out in a college library swimming with other finals-takers, most in sweatpants or leggings and T-shirts.

Our Take A Number series is exploring problems around the world through the lens of a single number.

Some high school students think of applying to colleges as a full-time job. There are essays and tests, loads of financial documents to assemble and calculations to make. After all that comes a big decision — one of the biggest of their young lives.

For top students who come from low-income families, the challenge is particularly difficult.

When La Guardia Cross first heard his wife was having a child, "it completely caught me off guard. I didn't feel ready."

By the time his daughter Amalah was born in 2014 — although still freaking out — he got out his camera and started recording. The hospital room — him holding his little baby in his arms. Amalah sleeping. Amalah crying. Lots of stuff about diapers and poop.

There's been a lot of attention lately on low-income students on campus — mostly on how to recruit them and how to make them feel welcome.

For good reason: Pell Grant recipients make up about a third of the undergraduate student population in the U.S., according to the College Board. And often, their experiences in college are very different than their wealthy classmates.

A teenage brain is a fascinating, still-changing place. There's a lot going on: social awareness, risk-taking, peer pressure; all are heightened during this period.

Until relatively recently, it was thought that the brain was only actively developing during childhood, but in the last two decades, researchers have confirmed that the brain continues to develop during adolescence — a period of time that can stretch from the middle school years into early adulthood.