In December, China claimed the top spot on the Program for International Student Assessment — PISA — which tests 15-year-olds around the world in math, reading and science every three years. The 2018 test results marked the third time that Chinese students have topped the ranking since students from Shanghai first participated in the test 10 years ago.

In 2018, 662,100 Chinese students chose to study abroad. If the Chinese education system really is the best in the world, why are Chinese students so eager to leave? These five things help explain.

1. Chinese students work long hours but remain among the least satisfied

The PISA bragging rights eclipse a few important details. First, this wasn’t a representative sample, as students taking this test came only from Beijing, Shanghai, Jiangsu and Zhejiang — two top-tier cities and a pair of provinces on the eastern, more developed area of the country. Education scholars have already critiqued PISA as a valid global measure of education quality — but analysts also are skeptical about the selective participation of Chinese students from wealthier schools.

Second, Chinese students, on average, study 55 hours a week — also No. 1 among PISA-participating countries. This was about 20 hours more than students in Finland, the country that PISA declared to have the highest learning efficiency, or reading-test-score points per hour spent studying.

But PISA analysis also revealed that Chinese students are among the least satisfied with their lives. My research suggests that this high level of dissatisfaction, in part, drives many privileged urban youths to leave China.

2. Students look overseas for a more well-rounded education

Their top destination of choice, by far, is the United States. The 1.1 million or so foreign students in the United States in 2018 included 369,500 Chinese college students and those on temporary education-related employment. Studies have documented pronounced increases in the number of Chinese students arriving in U.S. secondary schools in recent years.

What motivates the vast majority of Chinese students to study in the United States? My book focuses on this new wave of undergraduates from mainland China in U.S. higher education and draws from 507 online surveys with students. I also conducted 108 interviews with students in both Chinese high schools and U.S. colleges. I find that more than 90 percent of these students in the United States are privately funded, relying on their own families for support.

These interviews suggest that students are motivated to study abroad because of disappointment with the Chinese education system, which they assert “stifles creativity” and “entails hellish hours of studying.” The ambition to get into a good college without submitting to extreme studying brings them to the United States.

Studying abroad offers liberation from China’s test-oriented education system. Ironically, many of their parents succeeded within this system and obtained professional jobs and middle-class status. Yet parents now want to provide alternatives for their children — and educational opportunities that afford a more well-rounded experience unbridled by test scores than what they themselves experienced.

3. China’s overseas students are ambitious and anxious

This ambition to experience an alternative education system does not come without anxiety — lots of it. Chinese schooling is imbued with anxiety, and the privileged who leave to study in the United States are not immune from it. For many Chinese students applying to U.S. colleges, the admissions process can appear both alien and whimsical, requiring entirely different materials such as personal statements and recommendation letters, along with activities that are not part of the test-oriented Chinese system.

Chinese students also report feeling anxious about their grades once they start studying in the United States. Class participation can be a challenge, as the Chinese system rarely encourages or expects students to speak up.

And they are concerned about whether a U.S. education is really worth it, as the souring U.S.-China relationship makes them “political cannon fodder” and creates anxieties related to student visas and U.S. political scrutiny. U.S. intelligence officials, for instance, accused one Chinese student of attempting to recruit spies for the Chinese government.

4. Studying abroad can offer a second chance

Not all the Chinese students in my study were academically strong. Interviewees sometimes painfully recalled their teachers and peers in China ridiculing them for being academically weak. These students saw the opportunity to study at a U.S. college as a second chance to prove themselves.

The Chinese education system, in contrast, doesn’t give many second-chance opportunities. The college entrance examination — the Gaokao — takes place only once a year. These scores alone determine whether and where students go to college and, often, what they study.

Interestingly, Chinese students who stayed longer in the United States were less likely to report that they worked harder than their U.S. peers — and this held true after taking into account academic, family and institutional backgrounds. This finding resonates with the classic assimilation theory: The longer migrants stay in the host society, the more they resemble the members of that society.

5. The number of Chinese studying in the United States has begun to plateau

In the 2018-2019 school year, the total Chinese student enrollment in the United States rose 1.7 percent, the slowest annual increase over the past decade. In the long run, a slowdown in Chinese students studying abroad is inevitable, given the decrease in China’s college-age population and the cooling of the Chinese economy, among other things.

In the short term, hostility in U.S.-China relations could dampen the appeal of a U.S. education. Britain, in fact, recorded a 30 percent surge in Chinese applicants in 2019, challenging the U.S. global dominance in higher education.

In 2020, hundreds of thousands of Chinese students will again vote with their feet and their money and look to study abroad, buoyed by a strong ambition to combine the best parts of Chinese and Western education and better their future. Institutions around the world have welcomed them with open arms. Though President Trump remarked at an October news conference that “we want all the people that want to come over from China,” how long will the United States remain the top destination for Chinese students? Time will tell.

Yingyi Ma is an associate professor of sociology and a senior research associate in the Center for Policy Research at Syracuse University’s Maxwell School of Citizenship and Public Affairs. She is the author of “Ambitious and Anxious: How Chinese College Students Succeed and Struggle in American Higher Education” (Columbia University Press, 2020).