To require children to be age 5 by Sept. 1 to attend kindergarten, rather than by Dec. 1 under current law. This earlier age cut-off would be phased in one month at a time over three years, starting in 2013. A child who would have been eligible under the current requirements could still attend if the parents "opt in" by notifying the school by June 1. The phase-in and "opt-in" was negotiated because school districts get money from the state for each kindergartner, whose numbers would be reduced during the transition period.