The most important thing

She was a waif, thin-limbed and big-eyed, quiet and stubborn.

One of eight children living in her household, she was an unplanned child born after her father had begun his relationship with her stepmother.

Her own mother's whereabouts were unknown to us, as were the circumstances that brought her to live with her father and his wife, and what that woman must have thought when this child arrived at their door – living, breathing proof of her husband's philandering – in need of a place to live.

The families at our middle school are more fluid and of the moment – of the need – than of legal tie. Parents, children, brothers, sisters all may have different last names, and kudzulike family trees reach out and wrap around children with different fathers, mothers, grandparents.

She lived in the shadow of her older half-sister, who was streetwise, tenacious, and often mean. Her stepbrother was killed in gang violence, and two other stepbrothers had fallen into some bad activities, according to her father. He was unemployed, and the family moved frequently, three times in one academic year.

I was helping her with her high school application. This is the biggest part of my job, assisting the eighth-graders and their families in choosing a school that is safe, a good academic fit, and another step in their walk away from poverty.

But there was a problem. She didn't have a birth certificate. She had never had a birth certificate.

"Do you know where she was born?" I asked her father.

"Of course, I know where she was born," he told me, the slightest bit of offense in his voice.

But he couldn't get the birth certificate, because he wasn't listed on it. Only the mother was. She was in a bad way, he said. She didn't have a permanent home and would be difficult to track down.

The deadline for high school applications was fast approaching. Maybe the child could write the state for a copy of her birth certificate herself? I found a form online, which I helped her fill out in my office.

She copied the spelling of her mother's name from a financial aid application that her father had completed.

A legal government ID – a driver's license – was required, so I wrote a letter on her behalf telling them that she was only 13 and didn't have a license yet.

One week later, the state returned the form: no ID, no certificate.

But on the bottom of my letter, a kind clerk had scrawled a short message. On behalf of the school it was possible for me to request the birth certificate, if I included a copy of my own driver's license.

I mailed a new letter that day.

By now it was Christmas and my office had became a clearinghouse of high school applications as well as a hiding spot for the gifts I had bought for my own two children. On the last day before break, two eighth-graders posing as Mary and Joseph went from classroom to classroom in our own tradition of Las Posadas.

The girls received stockings full of presents, and then we all ate Chick-fil-A.

When we returned to school, the birth certificate was waiting in my mailbox. One last present: Here was the piece of paper that connected the girl with her mother, that proved she existed – the very opposite of what poor children like her are so often made to feel.

She could register for high school now. She could go on to college. Join the military if she wanted. Get married one day.

Sometimes it seems there's so little we can do for our students; and sometimes, when we're fortunate, there's a lot.

I climbed the stairs to the eighth-grade homeroom two at a time. "Here," I said as I handed her the piece of paper. "This is the most important thing I'm ever going to give you."