For these 5 schools, 4 years. They are following the example of another 3 schools nearby that have been doing it for 10 years.

Oh, on re-re-reading the article, one of the criteria for judging the success of the choice program is lowing the gap between the achievement of black and Hispanic children and that of the white and Asian children. That might be something that the schools (particularly working with the schools at younger levels) can have an effect on.