An Iowa school district accused of sending students to secluded, padded rooms for even minor infractions said it will stop using the disciplinary measure by the start of the next school year.

Iowa City school Superintendent Stephen Murley said in an email Tuesday night that the district has eliminated seven of its seclusion rooms and plans to eliminate the rest by next fall. Officials have said the rooms are primarily intended to hold students who pose threats to themselves or others.

A state Education Department review released in June determined that the district broke state and federal law by occasionally sending students to seclusion rooms for having a bad attitude, using foul language or being out of instructional control, among other reasons. The department reviewed more than 450 incidents involving more than 60 students were sent to these rooms over a one-year period starting in December 2015.

The district subsequently created a task force, which recommended the district reduce use of the rooms and stop referring to them as "time-out rooms."

It's unclear what method or practice will be used in place of the rooms. Murley said in his email that "the district recognizes the role of restraint and seclusion in providing a free and appropriate public education for all students in a least restrictive environment within our schools and is seeking ways to improve our practices."

It's also unclear what specifically led to the decision announced Tuesday. Murley didn't immediately reply to messages seeking comment that were left Wednesday.

The American Civil Liberties Union and six outside attorneys have filed a petition with the Iowa Education Department asking that it ensure seclusion and physical restraints are used only for emergencies and as a last resort, and are never used to punish children.

Iowa is one of only five states that allow seclusion or restraints when there's no physical threat, according to the ACLU. Twenty-nine states have banned the use of seclusion or restraints to discipline or punish a child.