Practising for a marching performance, teacher Shen Yin's five to six-year-old pupils respond without hesitation to her Mandarin Chinese instructions.
Yin, from Beijing, is one of three Chinese teachers at Woodstock elementary in Portland, Oregon.
Down the corridor, the nine to 10-year-olds in Jessica Bucknam's class are playing card games to learn the Mandarin for mathematical terms. "I like learning all this stuff in Chinese," says pupil Isabel Weiss. "My friends think it's cool."
Next door, beneath walls lined with Chinese posters, a flurry of hands go up to answer questions Liduan Hugel poses her eight to nine-year-olds as part of a reading comprehension exercise. Not a word of English is spoken.
Half of Woodstock's 343 pupils spend half their day taking lessons entirely in Chinese. They are part of a groundbreaking initiative that US government officials hope will serve as a pilot for the wider introduction of the world's most widely-spoken language into US schools.
The scheme is the first of 24 partnerships the Bush administration wants to see between education authorities and universities, to develop curricula to teach "critical need languages".
Last September, the scheme received $700,000 from the US defence department to work with the Oregon university to devise a model Chinese curriculum that schools across America can adopt.
It will be designed to produce 18-year-olds with near-native fluency and the option of further Chinese study at university.
Woodstock is where the detail is being worked out. Pupils must master 150 of Mandarin's 3,000-plus characters yearly, says principal Mary Patterson.
By 11, they must be able to converse with adults and read basic Chinese.
It is one of the hardest languages for English speakers to learn, says Carl Falsgraf, the scheme's director. "Chinese has meaning-based characters whereas English has sound-based letters."
To build vocabulary, Ms Hugel employs mnemonic devices like rhymes. Ms Bucknam says Chinese tends to be less direct than US English, but she teaches writing the American way, "right to the point". Cultural nuance can wait.