A new PBS documentary follows four students and their families at dual immersion schools in San Francisco. The film offers evidence that the study of math, science and other subjects in more than one language gives students an edge, despite what some disapproving relatives might think. Also, a conversation with Deborah Fallows on living in China and learning Chinese. In Chinese, she says, rude is polite, brusque is intimate. And then there's the lousy Chinese name she was given.