The five-episode Post-00s focuses on teenage issues that include education, relationships with parents and confusion in interpersonal communication. [Photo provided to China Daily]

For instance, teens are often confused when their younger siblings are born.

After decades of family planning in the country, the second-child policy has created challenges.

Sending children abroad to study is another tough decision for Chinese families.

In the documentary, what Zhang's team has done is like what American director Richard Linklater did in Boyhood.

In 2006, Zhang chose some kids who were in kindergarten for his documentary on education. And he followed them for a decade.

In that period, the children have changed a lot.

For example, someone willing to make friends in kindergarten has become a teen who prefers life online. And a quiet boy has become an outdoor sports fanatic who rode a bicycle with his father to Lhasa from Sichuan province.

"Even the craziest screenwriter could not imagine this," says Zhang.

"Each kid is like a seed, and all of them need to be watered," he says.

"However, no matter how we water the seeds, a cucumber will not become an eggplant."

In the documentary, he finds that optimistic, extroverted and talkative students are preferred by parents and teachers, and are usually seen as models.

"I'd like to use the documentary to make people reconsider: Whether our current education system matches the new generation's needs? Whether our schools and parents are helping or harming the kids?"

He also says some parents are choosing unorthodox education systems that emphasize more on individuality.