On one of the first days of class at Dos Puentes Elementary School in Upper Manhattan last month, a new student named Michelle peered up through pale blue glasses and took a deep breath.
“Can I drink water?” Michelle, 6, said.
“Diga en Español,” her first-grade teacher, Rebeca Madrigal, answered.
“Can I drink agua?” she replied.
It was a start.
Dos Puentes, a three-year-old school in the Washington Heights neighborhood, is a dual-language program, which means that subjects, like reading and math, are taught in two languages with the goal of making students bilingual. Once seen as a novelty, dual-language programs are now coming into favor as a boon to both native and nonnative English speakers, and in areas around the country their numbers have been exploding.