Bursting into the classroom from recess , 15 children take their seats and face the woman they know as Ms. Yang. "What day is it today?"she asks, in Mandarin  Chinese. "Confucius' birthday!"the fifth graders shout in Mandarin. "Why do we celebrate Confucius' birthday?" "Because he's the greatest teacher in the history of China!"exclaims a brown-haired girl. She too is speaking Mandarin. English is rarely heard in Lisa Yang's class at the Chinese American International School(CAIS), despite the fact that few students are native speakers of Mandarin. The United States is actively trying to increase the group of students in"critical languages"such as Mandarin. The students at CAIS are way ahead in such a trend. Mandarin explosion in America Founded 25 years ago, this small private school in San Francisco, USA, does what few other American schools do: It produces fully fluent speakers of Mandarin Chinese, by far the most commonly spoken language in the world. Mandarin Chinese is suddenly hot in American schools. As China becomes the world's leading economy sometimes this century, schools in the U.S. are _ to add Mandarin to their roster of foreign languages or expand Chinese programs already in place. "It really is almost unprecedented . People are looking at China as a force to be reckoned with...And to ensure that the U.S. has the ability to conduct trade, and to work with the Chinese, certainly having an understanding of Chinese language and culture is an advantage,"said Marty Abbott of the American Council on the Teaching of Foreign Languages(ACTFL) . Cultural differences in teaching styles To develop Chinese-language programs has not been smooth. A shortage of trained teachers has made it difficult for some schools to join the race. When schools do get teachers, they often hire them straight from China, and the teachers usually suffer culture shock when they come to the   U.S. Robert Liu remembers his first two years in an American classroom. It was not an easy adjustment. "In China, students respect their teachers,"he said. Liu found that American students, however, expect an active teaching style. He had to use games to engage them rather than lectures. To avoid many of the problems with foreign teaching styles, the CAIS has been working with the Chinese government to improve training of teachers who are sent to the U.S. It can be inferred from the passage that  _  .
the students in Lisa Yang's class usually speak Chinese there are few American students in Lisa Yang's class we celebrate Confucius' birthday because he's the greatest teacher in the history of China in America the students don't respect their teachers