You'll never get under Jamie Rosenberg's skin with a lawyer joke.

The 39-year-old former mergers and acquisitions attorney has heard 'em all, including those comparing lawyers to snakes and sharks.

But the jabs he gets the biggest kick out of are the ones about lawyers who, in spite of their occupations, become ''human'' and develop big hearts.

All jokes aside, Rosenberg became that big-hearted attorney more than a decade ago, when a visit to a local school led him to co-found Adopt-A-Classroom. Today, on its 10-year anniversary as a full-time program, the Miami-based nonprofit assists 30,000 classrooms and teachers throughout the United States and its territories such as Puerto Rico and Guam, and its donors have provided $10 million in money and supplies to classrooms.

The idea came to Rosenberg in 1988, when he visited a private school in Miami-Dade run by the Easter Seals Society, where he was mentoring a student.

''It bothered me how much they were missing,'' he recalls.

The most basic supplies, from pencils to chalkboard erasers, were scarce. Books were tattered, with pages missing. Even construction paper was in short supply.

''Teachers already don't receive the best pay, and many take care of these sorts of expenses out of their own pockets,'' he says. ``I wanted to do something about that.''

He called a friend and within a few days, his nonprofit was born.

Rosenberg, who grew up in West Palm Beach, could have taken a more lucrative path in life. He attended the prestigious Phillips Academy Andover boarding high school in New England, Vanderbilt University in Nashville, and the University of Miami Law School.

His brother's a doctor. His sister was an attorney and now is a judge.

But, he says, ``I've always had this thing about charitable work. It's in my DNA.''

Friends say as a kid Rosenberg volunteered for various homeless aid programs around Palm Beach County. In college, he opted for the Alternative Spring Break program that had him spending his breaks volunteering in soup kitchens and homeless shelters.

Still, when Rosenberg finished law school he dove head first into his job at Akerman Senterfitt, one of the largest law firms in South Florida.

Moving from practicing law to running a nonprofit wasn't a matter of disillusionment, Rosenberg says.

''I loved the law and the practice of law,'' Rosenberg says. 'But I had been looking for something, something more fulfilling about which I could say, `This is my mission.' '' He found it in 1998 when he mentored a boy at the Easter Seals school. The boy had suffered a stroke at age 3. A frequent ritual involved Rosenberg offering the boy a high-five palm slap, but the boy always held up a clenched fist -- a result of partial paralysis.

OVER THE EDGE

Rosenberg had already been thinking of how to help teachers with classroom supplies when he arrived at school one day and offered his usual high five. The boy opened his palm and slapped Rosenberg's.

''It was a small thing. But he got some of his movement back, and that experience really moved me -- just pushed me over the top,'' Rosenberg says.

Rosenberg called Max Holtzman, an old friend from UM Law School, and asked for his help in starting Adopt-A-Classroom.

'He pointed to Adopt-A-Highway and said, `Let's use that model for a classroom,' '' said Holtzman, who works for the U.S. Department of Agriculture. ``I said I loved it. Literally the next morning we met at the Van Dyke Cafe on Lincoln Road for a true back-of-the-napkin story and scribbled out plans for the program.''

The program started off part-time, run out of Rosenberg's office, his car, and wherever else he could make calls and set up meetings. The first donation came a few months later -- $500 from Locus Architecture in Coral Gables. Within six months, Adopt-A-Classroom had gathered so much steam that Rosenberg quit law to lead the nonprofit full-time. Holtzman continued to work as a lawyer and later a developer.

Today the nonprofit is headquartered on the second floor of an office building in Miami's Design District and employs a modest staff of five, including Rosenberg, whose title is founder and executive director.

Teachers register their classrooms at www.adoptaclassroom.com, along with a wish list of items they need for their classrooms.

In turn, donors can select a teacher/classroom to support.

Minimum donations are $25 and go into an account from which teachers can draw funds that go directly to vendors who work with Adopt-A-Classroom.

In her classroom at Arvida Middle School in West Kendall, Rebecca Mazzarella, who teaches eighth-grade history, is queen.

She buzzes about, constantly trying to pollinate the minds of her students. She keeps them on their toes with questions and a sharply pointed finger. ``You! Tell me what was significant about this date in American politics!''

Mention Rosenberg though, and Mazzarella melts.

''It is so wonderful how stereotypes [about lawyers] can be wrong,'' she says. ``I was delighted when he brought Adopt-A-Classroom to this school.''

HELPED IN MANY WAYS

Mazzarella says Adopt-A-Classroom has helped with several items -- supplements to teaching materials, ''small gifts for hard work,'' even basics like pens and pencils.

''Teachers pay for these things out of pocket,'' she says. ``When you get adopted though, many of those out-of-pocket costs disappear.''

There are also intangibles, Mazzarella says. One of them is Julio Llanes, a BankAtlantic executive who adopted Mazzarella's class six years ago.

Llanes, the bank's vice president of market management, says that while he was motivated to adopt Mazzarrella's class because of the funding and supply needs, he was more motivated by the opportunity Adopt-A-Classroom provided for him to share his expertise with young minds.

''It's a passion of mine, and I thought it was a great opportunity to talk with the kids about the importance of savings and establishing good credit,'' Llanes says.

Considering the subject matter, ''you wouldn't think they would care at their age about these sorts of things. But they love him and get excited every time he comes,'' Mazzarella says of Llanes.

Llanes says his curriculum is visual -- ``numbers on the chalkboard, current events discussions, explanations like Dell Computer and how much an original share of Dell stock is worth today.''

Rosenberg beams at Llanes' story, because it reflects another corporate professional sharing work-related knowledge with kids. And he could talk about such examples all day.

But all work and no play can make even the most charitable former lawyer cranky. So when he can catch a break Rosenberg, who lives in Miami, plays with his children -- ages 2 and 4, reads, or sneaks off to the movies with his wife Lisa, a grant writer.

He loves to travel. And in his perfect world, if he were not running Adopt-A-Classroom, he would be a full-time teacher.

On his way to a Liberty City elementary school to meet with faculty and speak to students recently, Rosenberg struggled to contain a smile.

''What you do with your life is a choice,'' he says. ``It's easy for me to say it now, but I'm pretty sure I made the right one.''