The archive of First High School of Taoyuan county in Hunan province has collected a glittering array of the school's achievements over the past century. But what always brings a smile to its current principal, Yan Liguo, is a letter and a payment.

One day in September 2013, Yan received an anonymous bank draft in the amount of 600 yuan ($87) folded in an envelope, along with the code of a People's Liberation Army unit. It had been sent from Changchun, Jilin province.

"I was baffled. Why would someone send a check from miles away?" he said.

A few days later, a letter arrived at his office from Zhou Honglei, a student at the Air Force's Aviation University who had graduated from high school in Taoyuan two months earlier.

Zhou said in the letter that the check was the first allowance of his life. Though the amount was small, he wanted to donate it to his alma mater.

"Please use it to assist students under financial strain. I hope they can work hard and change their destiny. Meanwhile, I am looking forward to seeing more passionate young adults devoted to the military to guard our country," the letter read.

"I wrote it simply because I wanted to reciprocate with the first income of my life," he said. "I feel a strong bond with the high school in Taoyuan."

Over the past 40 years, 72 graduates from the high school have been recruited to become pilots by the PLA Air Force. In 2016, it recognized the school as a high quality candidate pool.

Yan said the school's impressive record for nurturing future pilots is a reflection of the well-rounded education it provides.

"For years, we have been pushing for a teaching method that allows students to take charge of the class," Yan said.

It's not unusual for a student at the high school to step to the front of classroom to host a discussion or demonstrate how to solve a math equation.

The scene might be common in any of the country's international schools or top-ranked high schools in large cities, but some students at Taoyuan have to break out of their comfort zone to speak up.

Taoyuan county is a major exporter of labor, with about one-fifth of its population seeking employment outside the region as migrant workers.

At the high school, more than 60 percent of the students were born into a single-parent family or are separated from their migrant parents, Yan said.

"It is an effective way to improve their presentation skills and ability to handle pressure."

He added that high test scores are not seen as an express ticket to success at the school.

"Children growing up in rural areas are often fed the idea that they can monetize their education to earn a living," Yan said. "Our teachers help broaden their mindset."

Zhou, for example, was a timid and reserved boy when he enrolled in 2010. He said it was more than his physical ability and academic performance that got him through the PLA's rigorous pilot screening process.

"The high school is a melting pot of students with a variety of backgrounds, and I have learned to have empathy and interact with different personalities," he said.

"Pilots work under extreme pressure. At the flight school, I have faced blistering criticism that deals a blow to my confidence. But years at the high school have trained me to be strong and persevere."

Zhou still remembers the hazy afternoon in his senior year when he wandered onto the playground during a free period, looking dejected.

"My teacher saw me and held an umbrella to walk with me in the drizzling rain, unknotting and dissecting my concerns and fears," he said. "In that misty drizzle, I saw a clearer future for myself."

Wang Xiaoyu contributed to this story.