This year, the state passed new regulations that would require school districts to adjust their discipline policies to reduce suspensions for nonviolent offenses, provide educational services for students suspended for long periods and address the disproportionate suspension rates of students of color and those with disabilities.

In January, U.S. Secretary of Education Arne Duncan and Attorney General Eric Holder visited Baltimore to debut new discipline guidelines to help districts across the nation tackle the same issues.

During that visit, Duncan also cited pre-K suspensions, including Maryland's, as an indicator of why such standards were needed.

Under former city schools CEO Andrés Alonso's administration, Baltimore was held up as a leader in finding alternatives to pushing students out of school. During his six-year tenure, which ended in June 2013, the district cut the number of suspensions from 16,752 to 8,653.

But in schools, there's been debate about whether or not the pressure to keep numbers down has resulted in teachers and students being forced to suffer unsafe and disruptive conditions.

Thornton said he believes that "you can reduce suspensions and not improve climate."

He asked central office staff to find another data point besides suspensions and expulsions that could be used to determine whether a school has a positive learning environment.

The policy changes about pre-K suspensions were among several made to the district's student Code of Conduct for the coming school year.

Some changes were to comply with new state regulations, such as revising the definition of a "short-term" suspension from one to 10 days to one to three days.

The bulk of the document, which in the past has been criticized as too lenient, outlines how schools should respond to student behavior, such as what warrants an automatic suspension. It provides levels of responses that principals are to follow before assigning a suspension or expulsion.

Last year, the district drew criticism for its decision to downgrade the consequences for a student who brought a switchblade, pepper spray or other weapon that is not a firearm to school and didn't use it to endanger another person.

Historically, that would warrant an automatic suspension, but officials said the code was revised to provide a range of options so that students weren't being suspended for actions like bringing a water gun to school.

This year, the code adjusts consequences for other behaviors such as bullying, serious disruption on school buses, unintentional physical contact with a staff member, breaking and entering, and making bomb threats.

Some of the adjustments are to make the discipline options more serious, while others give principals more leeway to mete out discipline on a case-by-case basis.

For example, students could receive a short-term suspension for serious cases of bullying under the new revisions, when previously the harshest punishment was an in-school suspension. And students can now be given an even longer suspension for attacking a bus driver.

But next year, a student who is caught breaking and entering won't automatically be suspended, and a principal will be allowed to impose an alternative consequence in cases where the offense doesn't involve an "imminent threat of serious harm to the school community."

The Code of Conduct also sparked debate at Tuesday's school board meeting for its emphasis on the time and resources needed to address poor behavior.

Commissioner David Stone asked: "Where in the Code of Conduct does it speak to the sacredness of instructional time?"

He said he has been confronted by parents who are concerned that their children are not getting the attention they deserve because principals and teachers are so preoccupied with attending to behavior issues.

"I'm worried about [those kids] getting help," he said, "but I'm worried about the 29 other kids who aren't getting attention."