The schools have a complicated relationship with tutoring. Generally, they discourage it: Riverdale requires students to specify on graded take-home assignments whether they have had assistance; Dalton asks families to exhaust the school’s resources first, and then if outside help is deemed necessary, the school’s learning specialists try to coordinate it. But if tutoring lifts students’ scores and grades, and thus their admission chances at the most competitive colleges, that can benefit the schools’ reputations.

At New York’s Private Schools, a Tutor for Every Class - NYTimes.com