The iSchool is considered a screened school in New York City, which means that the school has the ability to use students' middle school grades and test scores as criteria for admissions. While the iSchool has the ability to admit only top students, the school feels it is important to serve a diverse student body, one representative of the broader system. The iSchool believes firmly in informed choice, so primarily uses its status as a screened school to ensure that students want to be at the iSchool. The school does this through requiring prospective students to complete an online admissions activity, designed to assess students' interest in the school.
The online admissions activity is also used to help the Admissions committee think about which students will do well at the iSchool; those who really strive to be independent learners are those who will be happiest at the iSchool because they understand that the school is consciously moving them toward that goal, and appreciate that the reward will be greater independence in determining their academic path. It is also important to the school that students know what they're getting into - a high school that is offering a different instructional model. A demonstrated understanding of what that is and a genuine interest in being part of it are qualities that reveal to the admissions committee a good match.
The admissions committee reviews each application to get a better understanding of each applicant; the school prefers to have no set cut-offs, instead using a formula that will allow students who struggle in one area but stand out in another to have an equal chance of admissions.
Read more from an insider's perspective about the iSchool admissions process at: http://gothamschools.org/2009/12/03/high-school-admissions-an-inside-perspective/