Khadijah Williams stepped into chemistry class and instantly tuned out the commotion. She walked past students laughing, gossiping, napping and combing one another’s hair. Past a cellphone blaring rap songs. And past a substitute teacher sitting in a near-daze.

Quietly, the 18-year-old settled into an empty table, flipped open her physics book and focused. Nothing mattered now except homework.

“No wonder you’re going to Harvard,” a girl teased her."

Around here, Khadijah is known as “Harvard girl,” the “smart girl” and the girl with the contagious smile who landed at Jefferson High School only 18 months ago.

What students don’t know is that she is also a homeless girl.

As long as she can remember, Khadijah has floated from shelters to motels to armories along the West Coast with her mother. She has attended 12 schools in 12 years; lived out of garbage bags among pimps, prostitutes and drug dealers. Every morning, she upheld her dignity, making sure she didn’t smell or look disheveled.

On the streets, she learned how to hunt for their next meal, plot the next bus route and help choose a secure place to sleep — survival skills she applied with passion to her education.

Only a few mentors and Harvard officials know her background. She never wanted other students to know her secret — not until her plane left for the East Coast hours after her Friday evening graduation.

“I was so proud of being smart I never wanted people to say, ‘You got the easy way out because you’re homeless,’” she said. “I never saw it as an excuse.”

“I have felt the anger at having to catch up in school ... being bullied because they knew I was poor, different, and read too much,” she wrote in her college essays. “I knew that if I wanted to become a smart, successful scholar, I should talk to other smart people.”

Khadijah was in third grade when she first realized the power of test scores, placing in the 99th percentile on a state exam. Her teachers marked the 9-year-old as gifted, a special category that Khadijah, even at that early age, vowed to keep.

“I still remember that exact number,” Khadijah said. “It meant only 0.01 students tested better than I did.”

Khadijah didn't get to Harvard by herself. Everyone else in the class of 2013 got where they are because just as they believed in themselves, others believed in them, encouraged them, educated them, challenged them and inspired them.

There are more Khadijah's out there - we can help them make it too. That is, if we care...