Public school superintendents listen up.

Abington High School, outside Philadelphia, just got one of its former students, billionaire private equity titan and philanthropist Steve Schwarzman, to donate $25 million.

How did the school do it?

Schwarzman, co-founder of Blackstone Group, told CNBC on Thursday: "I was asked. That's always the way something happens."

"It starts with a phone call and ends with a visit," he said on "Squawk Box."

The school needed $100 million but could only write a check for $75 million, Schwarzman said. "They asked me to fill the difference."

Abington officials said, "The donation is considered to be the largest ever given to an individual public school."

The money will help build a new science and technology center and allow for a "full-scale renovation of the 1950s-era high school building."

Schwarzman, chairman and CEO of Blackstone, said he required a computer literacy curriculum as a mandatory condition of his gift.

"They are going to start in the seventh grade and learn all the modern skills," he said, stressing the importance of technology "whether you're doing auto repair or working at Google."

Computers will be provided to students for use in school and at home.

Schwarzman told CNBC he recognizes that his gift is out of the ordinary.

"It's not part of our culture" to give to public schools, he said. "We just assume that someone else will take care of that."

Known as much for his generosity as his business acumen, Schwarzman has made education a centerpiece of his philanthropy.