“The city takes its responsibility to address any complaint very seriously,” Harry Hartfield, a spokesman for the Education Department, said. “Everyone is held to the same standard, and there is zero tolerance for the kind of educational failure alleged.”

There are roughly 250 Jewish day schools in the city, which range from secular to ultra-Orthodox. The ultra-Orthodox schools, many of which are in the Brooklyn neighborhoods of Borough Park, Williamsburg and Crown Heights, prioritize religious studies, particularly for boys.

The letter states that at the 39 yeshivas, children ages 7 to 13 receive only an hour and a half of English and math instruction combined four days per week. Other secular subjects are not taught at all, and English instruction for boys stops at age 13, the letter states. (Most Hasidic Jews speak Yiddish at home, and nearly a third of students in Jewish schools in New York City speak limited English, according to the Department of Education.)

The letter notes that girls tend to receive a better secular education. Naftuli Moster, the founder of Young Advocates for Fair Education, said that was partly because girls are not allowed to study the Talmud, leaving more time for secular subjects. Also, since many men devote themselves to religious studies, women are expected to be able to work outside the home to support their families.

The Education Department said it was finalizing requests that the superintendents would send to the yeshivas mentioned in the letter. If, based on the responses, a superintendent determines that a yeshiva is not providing instruction substantially equivalent to that in public schools, the superintendent will work with the yeshiva to develop a remediation plan. In the worst case, if the department determines that a school’s instruction was not equivalent, ultimately, children who attend the school would be considered truant. The letter and the Education Department’s response were first reported by The Jewish Week.