The Portland School Board on Tuesday put off a proposal to start high school later in the morning, with members saying they had not sought enough public input and needed to study the issue more.

“I realized we hadn’t done a very good job of keeping our public involved,” said Marnie Morrione, the chairwoman pro tem.

The board is changing the times for all schools because it decided in December to add 20 minutes to the school day, starting this fall.

After a series of votes Tuesday night, the board agreed to keep the high school start times at 8 a.m., and add the 20 minutes to the end of the day, meaning the high schools will get out at 2:30 p.m.

The changes to the schedule mean the district will now use city buses to transport high school students, with some exceptions to accommodate students who live on islands and need to catch a 2:45 p.m. boat to get home.

Also Tuesday, the board voted unanimously to approve a $102.8 million school budget and send it to the City Council for consideration. A public referendum on the budget will be held May 12.

At earlier board meetings there was consensus among members that they wanted to start high schools later, based on numerous studies that say test scores improve and high school students do better if they start school later in the day.

But at a public hearing Tuesday evening before the board’s regular meeting at Casco Bay High School, about a dozen high school students said they opposed a later start time. Several said it would conflict with after-school sports and activities, part-time jobs and caring for younger siblings.

“There are a lot of students who are against the proposed change,” Deering High School senior Mohamed Nur told the board. “I believe it is very detrimental to student success in all three high schools.”

Nur, who previously was a student representative on the school board, urged members to “talk to the students, since they are the group of people who will be most affected by this change.”

More than two-dozen people spoke at the public hearing, and board member Jenna Vendil said she had received about 100 emails on the proposed changes.

The board asked the superintendent to form a task force to study a later start time for high schools, and to survey students about their interest in starting the day later.

The board also voted to change start and end times for elementary and middle schools.

Currently, elementary schools begin at 8:55 a.m. and end at 3:05 p.m. Some schools, including East End and Riverton, have special morning programs that start earlier.

The changes approved by 7-1 votes on Tuesday were:

• Elementary School Group 1 (East End, Longfellow, Lyseth and Presumpscot) – 7:45 a.m. to 2:15 p.m.

• Elementary School Group 2 (Hall, Riverton, Ocean Avenue and Reiche) – 8:05 a.m. to 2:35 p.m.

• King Middle School – 7:55 a.m. to 2:25 p.m.

• Moore and Lincoln middle schools, and Bayside (formerly West School): 8:35 a.m. – 3:05 p.m.

Board member Laurie Davis voted against the changes, saying they did not allow enough time for island students to catch the 2:45 p.m. ferry.

“I think we can do better,” Davis said, suggesting additional school time could be found by using the current early release days for instruction instead. “It is wrong to treat the residents and students and families in one neighborhood differently than we treat the rest of the city.”

Currently, island students are dismissed early to catch the ferry.

Under the new schedule, the extra 20 minutes will create a 6½-hour school day for students starting this fall. There will be fewer days in the school year – 178, down from 180 – but students will end up attending 46 more hours of class.

Maine requires that students attend a minimum of 175 instructional days a year. Local school districts set the length of their school day, but under state law the average instructional day must be at least five hours long, and no individual day can be less than three hours.

The school district is currently in discussions with Metro officials to work out a transportation plan for high school students.

Supporters say a deal with Metro would free up the school district’s 20-bus fleet for the elementary and middle schoolers and break the transportation logjam in the morning, in addition to boosting ridership for the city bus system. It would also allow students who live within two miles of a school to take a bus to school; those students are not allowed to ride the traditional yellow school buses.

Critics say Metro would be less convenient for students who live farther from school and are now served by yellow buses because they may have to walk farther to get to a Metro stop. Some parents have questioned how long the Metro bus trip would take, but Metro officials say it would be about the same time it takes a yellow school bus.