The school year will begin Thursday without a citywide smartphone ban in place, as city officials instead take time to study best practices.

But individual schools can, and should, enact bans on their own, Schools Chancellor David Banks said Wednesday.

“We are strongly encouraging our schools to take a look at this and create ways to prevent kids from having cell phones while they’re still in the class,” Banks said during a town hall-style appearance on WABC-TV.

Banks said he expects well over half of city schools will have some restriction in place this year. While some parents are anxious about being unable to immediately reach their kids, Banks said the harmful effects of cellphones are by now well established.

“They’re distracting,” he said. “We found that they presented lots of safety issues with cyber-bullying. And we don’t see any strong academic reasons for having the phones in the school.”

A cellphone ban is not the only major policy issue looming over the school system. The city is also trying to comply with a state law mandating lower class sizes that’s being phased in over five years.

“We are now clearly on the road, moving forward, to make sure that all the children of New York City get what the rest of the children of the state have, which is lower-class sizes,” Michael Mulgrew, president of the United Federation of Teachers said.

Mulgrew and elected officials on Wednesday touted the efforts of I.S. 145, a Jackson Heights school already meeting the mandate, with its sixth-grade classes capped at 23 students.

“We have over 600 schools right now that have enough space to lower their class sizes for the entire school,” Mulgrew said.

But Banks says the problem is complicated, even as city officials on Wednesday marked the start of the school year by celebrating the opening of 24 new school buildings, creating more than 11,000 new seats.

Banks, joined by Mayor Eric Adams and other city officials, spoke at a ribbon-cutting for the LEAD (Leaders of Excellence, Advocacy, and Discovery) school in the Bronx.

“The new additions that we're getting, they help us with respect to meeting the class size law,” Banks said. “But by the time we hit next year and beyond, there are going to be some more difficult choices that are going to have to be made.”

“You will need 10,000 to 12,000 more teachers, where there is a national teacher shortage. So the question becomes, do you lower your standards to get more teachers?” he added.

Banks has warned other possible solutions could include capping enrollment at more desirable schools.

Beginning next year, 60% of city classrooms must meet the state-imposed mandate, which caps class sizes at 20 for kindergarten through third grade, 23 for fourth through eighth grade and 25 for high school.