School's in.

With optimism, pomp, and dozens of actual bells sounding a noisy chime, officials formally opened the school year for 130,000 students in Philadelphia public schools Monday morning, marking the first time in modern history that city students returned to school before Labor Day. (That shift, officials said, comes largely to maximize instruction early in the school year.)

"We are beyond excited to start the 2018-19 school year," Ariel Lajara, principal of Muñoz Marín Elementary, a K-8 school in North Philadelphia, said to the dignitaries — Mayor Kenney, Superintendent William R. Hite Jr., most of the new school board, and other officials — who gathered in the schoolyard for the traditional bell ringing.

The school year got off to a hot start, with temperatures reaching 90 in Philadelphia Monday, and with heat indexes forecast to reach triple digits, the school district announced that students would be dismissed at 1 p.m. Tuesday and Wednesday.

The school year starts with the new governance structure in place. The School Reform Commission is gone; the nine-member, mayoral-appointed Board of Education now presides over the district. Officials hope families will see no practical differences in schools, though Hite said his job has changed as a result.

"It feels like a new start for all of us," Board President Joyce Wilkerson said, adding that the first day "really does set the tone for what's going to happen for the rest of the school year."

City Councilwoman Jannie Blackwell said that the new governance structure gives an air of possibility to the new year.

"It's a different kind of feeling, a different kind of expectation," Blackwell said. "This feels different."

Kenney, who "put it all on the line for public education," by engineering the end of the SRC and a return to local control, was in good spirits, saying the bells reminded him of first days at his own grade school, Our Lady of Mount Carmel at Third and Wolf Streets, where a nun in full habit rang an old-school bell to start every school day, Kenney said.

Fixing the city's schools, where, even amid progress, just a third of students can read on grade level and 67 percent graduate on time, is the key to everything, Kenney said — to lifting people out of poverty, to keeping middle-class families from moving to the suburbs when it comes time for their kids to start kindergarten.

"This is the most important economic investment we can make in our city," said Kenney, adding that without education, "nothing else matters."

Though he wants stability to be the byword for this school year, Hite said, there are some new things, too — instrumental music in all schools, expanded arts opportunities, more modernized classrooms, ninth grade academies in all comprehensive high schools.

And at Muñoz Marín, the 650-student school featured some new bells and whistles, too. The school got a new heating and air-conditioning system and other upgrades, including a renovated library. (The school does not, however, have a librarian — fewer than 10 schools in the district now have one.)

As he wove his way through hallways, Lajara, the principal, waved to new students and greeted returning ones warmly, shaking parents' hands and asking about their summers. He said he was delighted by the early start to school, and if the school calendar does move up by another week next year, as he has heard, he would welcome that, too.

"The earlier the better," said Lajara. "If it was up to me, we'd have even more instructional days."

Temperatures hit 90 Monday afternoon and looked to crack the mid-90s the next two days. Teachers' union officials have raised concerns about starting school in August, when the school system's mostly un-air-conditioned buildings have had months to accumulate heat — but school officials pointed out that there's little temperature difference between late August and mid-June, when school used to end.

The August start was fine with Evelyn Rosado, who dropped daughter Ruthmary Vasquez off at Muñoz Marín early to start sixth grade.

"Now, it's my vacation," joked Rosado, who hugged her daughter hard.

As students streamed in, the mother and daughter were philosophical about their hopes for the new school year.

"I want her to get good grades," Vasquez said of Ruthmary.

"I want," Ruthmary said, "to make my mom proud."

Officials criss-crossed the city, visiting multiple schools to mark the first day of classes.

At Kensington Health Sciences Academy, teacher Rachel Newman, launching a global leadership program at the school, said she had high hopes for the year. Previously, the school had three career tracks — dental assistant, pharmacy tech, and nursing — but there were not enough spaces for all students to land in one of those tracks, so some students had no academic focus.

The new global leadership track, Newman said, will equip students to take action to solve problems they see in their neighborhoods and in the world.

What things, Wilkerson asked the students, did they want to change?

"I want to fix the violence," said Dynasty Perez, a sophomore. "Children are dying every day."

Board member Leticia Egea-Hinton, who was trained as a social worker, looked at Perez. Becoming an activist is important work, she said.

"I'm doing it on the board," said Egea-Hinton. "That's what I signed up for."