It takes only a second and the transformation is complete. Ying Roucheng, the visiting scholar from the Peking People's Art Theater, has become the angry wife.
''You see, in this scene,'' he explains to the students gathered around him, ''the husband and wife have quarreled and they are sitting back to back. The timing has to be just so. Slowly, they turn toward one another,'' he continues, turning in his chair, never losing his character even as he speaks to the audience.
''Then there is one note when the eyes meet - tong!'' He smiles. ''It really works.''
Once again he is Ying Roucheng, sitting at a simple, round black table in a rehearsal room at Wellesley College and talking about traditional Chinese drama.
Ying plays many roles. He is a scholar who has translated Shakespeare into Chinese and Chinese masterpieces into English. He is a leading actor in his own country and is known to American audiences for his performance as Emperor Kublai Khan in the television film ''Marco Polo.'' He is an experienced director.
And this year he has taken on yet another role. This year he is a cultural ambassador, bringing Chinese drama to the United States.
As a visiting professor at the University of Missouri in Kansas City, Ying is teaching two drama courses and has directed American students in a production of the Chinese play ''The Family,'' which he translated.
During the year he will visit 10 universities to talk with theater students.
Next year, in turn, he will take some American drama back to China. While here he has been translating ''The Death of a Salesman'' and arranging for author Arthur Miller to go to Peking to work on the production this spring.
The exchange of drama is important, according to Ying.
''People should understand each other better, not just in politics,'' he said in an interview. ''We need to realize that people living on both sides of the Pacific are people, the same dreams, the same frustrations.''
''A good production of a play will tell you much more than reading a history book,'' he said.
But staging a good production of a Chinese play in this country or an American play in China is not a simple task, because more is involved in a play than the words in the script, Ying said.
''That is why I should be here,'' he explained. ''I could have translated the play and sent the script over. It is not the same thing.''
The two cultures have differing acting methods and differing ways of using a stage. Actors in either country need to learn the methods and techniques of the other to perform the play effectively, he said.
Traditional Chinese theater is less realistic than most Western drama, Ying said. In a typical Western play, the stage is a specific place at a specific time, as though a wall of a room had been removed to allow the audience to see the action.
Chinese actors are ''never bothered'' with conventional time and space, Ying explained. ''We never had a fourth wall in Chinese theater and we were very happy until the 20th century.''
Chinese actors also use fewer props and less scenery, he said. ''The actor is the center of it all.''
And that actor is more likely to use a variety of tricks to create illusion and drama. They may use mime to indicate a doorway or manipulate the feathers on a headdress to show a shift in the character's mood. Some are masters of changing painted faces in the middle of a performance.
Often the tricks are family secrets that are guarded carefully, Ying said.
But it is not the actors' tricks that Western actors should learn, Ying told students at Wellesley. It is their concept of the stage, the way they use it, that is most important for American actors to understand.
''You have to accept that stage reality is not the reality of life,'' he said.
American actors are usually eager to move around in stage situations where, often, standing still would be more effective, Ying said. He has had a very hard time getting American actors not to touch during love scenes in Chinese plays, he added.
In China, Ying told students, acting students begin their training at age 8, studying singing, dialogue delivery, character development, and the martial arts for dancing and fighting scenes. They also take a full program of liberal arts studies.
''You really have to be quite a person to be a Chinese actor,'' he said.
The problem is that some students concentrate on their acting skills and ignore the general studies, because it is the quality of their acting that will determine their futures, he said. ''And so we have some actors who can hardly read or write.''
Ying said he has been very impressed by the dedication of American theater students who carry full schedules of college courses and spend hours and hours in rehearsals.
''They work very hard. When I go back,'' he said, ''this is what I will tell them.''