As temperatures rose, ultimately topping 90 degrees, students arrived at Brookstown Middle Magnet Academy Monday morning dressed like they were going to church, complete with blue blazers for the boys.

Blazers along with white shirts and khaki pants make up Brookstown’s student uniform for the 2014-15 school year, which started Monday in East Baton Rouge as well as in East Feliciana, Iberville, Pointe Coupee and West Baton Rouge parishes.

“When you’re dressed up, your mindset is better,” said Principal Sean Joffrion, who served as assistant principal last year at McKinley Middle Magnet School.

The special uniform is part of a larger effort by Brookstown to establish order right away in hopes of making it easier to create a unique school culture.

The school has had limited time to do that because teachers weren’t able to move into their classrooms until Thursday because of extensive summer renovations; the gym won’t be finished until later this month.

While most of the students showed up in proper uniform Monday, Jonathan Dearbone was on hand for those who didn’t. The owner of Burning Sands International, a men’s fashion store on Plank Road, came armed with a coat rack full of blazers for students who might need a fitting. Dearbone said he first started wearing coats himself in the 1980s when he was in high school.

“We were into the ‘Miami Vice’ thing,” he recalled with a smile. “We got into trouble when we came to school with no socks.”

Tyronda Williams approved. Her daughter was one of 162 sixth-graders at the new school; there’s also 79 seventh-graders who will come to school Tuesday. The mother chose Brookstown because Joffrion used to be her high school teacher.

“Living ’round here, you need some structure. (Joffrion) means business,” Williams said.

A lot of new schools are opening in August, all trying to establish their respective cultures.

The East Baton Rouge Parish school system opened two on Monday, Brookstown and foreign language immersion school at Polk Elementary called BR FLAIM II.

As the school system expands its magnet program, 10 charter schools are opening at the same time. The total number of charter schools in metro Baton Rouge — public schools run via contracts with private entities — is increasing from 13 to 23, making the state capital second only to New Orleans in the prevalence of charter schools.

Overall, enrollment in East Baton Rouge Parish public schools stood Monday at 42,181 students at 87 parish schools. That’s a decline of 156 students from the 42,337 students enrolled in the parish school system on the first day of school a year ago, but it was a smaller decline than in previous years. Louisiana’s official enrollment count is not taken until Oct. 1.

Superintendent Bernard Taylor said he’ll have a better idea of enrollment over the coming days as things settle. Overall, Taylor declared Monday a successful first day of school, the best since he came to Baton Rouge from Grand Rapids, Michigan, in June 2012.

“I just feel like we had a very smooth opening,” Taylor said. “Hopefully, that’s a precursor for the year.”

Five of the 10 new charter schools are part of a reboot by the state-run Recovery School District, which first entered Baton Rouge in 2008, taking over low-performing East Baton Rouge Parish schools. Three schools now run by the Los Angeles-based Celerity Educational Group opened Monday.

Patrick Dobard, RSD’s superintendent, said Dalton and Lanier elementaries as well as Crestworth Middle School report enrolling 349, 416 and 273 students, respectively, which is a slight increase over last year’s Oct. 1 counts.

Crestworth’s enrollment had the largest increase, 116 students. That school, however, has added three elementary grades as well as taken in students from the closed Glen Oaks and Prescott middle schools, which had 321 students combined last year.

Dobard said Celerity impressed him with how quickly it got to business Monday.

“One thing that really stood out is you could see the school leaders immediately establish the cultural norms of the school,” Dobard said.

Another RSD school, Baton Rouge University Prep, or UP Elementary, is devoting considerable time to such matters.

The school, which has enrolled 104 kindergartners, held its first full day of school Monday; last week it had half-days. Its full day is an hour longer than the days of most other elementary schools in Baton Rouge.

It was an organized day. Principal Meghan Turner spent 45 minutes after breakfast in the cafeteria at the former Glen Oaks Middle training the 5- and 6-year-olds to behave as their new school demands.

The students had four teachers, and each one named their class after where they went to college: University of North Carolina, Allegheny, Arizona and Tulane.

Turner urged the students to get in “star position,” which meant they sat up straight with their hands folded in front of them.

“Way to go, Arizona,” she announced

“Nice job, UNC,” she’d say next.

“Studies have shown that when children sit up straight, their retention is better,” Turner said afterward.

Turner is a fellow with Boston-based Building Excellent Schools, a two-year training program that gave her the chance to pinch ideas from “schools that were blowing other schools out of the water.”

Twelve miles south, near LSU, Polk Elementary was busy as well. Like Brookstown, the school underwent summer renovations and looks almost new. Its teachers, though, had just four days to set up their rooms.

The school is also the home of BR FLAIM II. It’s an expansion of BR FLAIM — Baton Rouge Foreign Language Academic Immersion Magnet — located a mile north on the edge of downtown. BR FLAIM II will grow until the traditional Polk Elementary School is phased out six years from now.

The new magnet got off to a late start and has just 30 students, 20 shy of its capacity, though school leaders said they hope to add up to 20 more in the first two weeks of school.

Like the original foreign language immersion school, the students spend 70 percent of their day immersed in a foreign language, Spanish and a new addition to the school system, Mandarin Chinese.

Cayla Borruano, an assistant principal at BR FLAIM, said the point of teaching Mandarin Chinese is not immediately obvious to many in Baton Rouge.

“Some people say, ‘Why? Why Mandarin?’ ” she recalled. “I say, ‘It’s the most widely spoken language in the world.’ ”