By Waddling around in clown feet and sporting a crazy-bright clown wig, teacher Kaleisha London didn’t let anyone enter her fifth-grade classroom at Claiborne Elementary on Wednesday without smiling.

“This is a smile zone,” London told one glum-faced boy. “This is a no-frown zone.”

The smiles also were sparked by the place.

Claiborne’s 4700 Denham St. address has been transformed over the past two years.

The half-century-old school was torn down and replaced with a much larger $17.2 million, two-story building.

A crowd formed early outside Claiborne on Wednesday, the first day of the 2011-12 school year in East Baton Rouge Parish, with families waiting to enter the school.

“We’re ready for them, and they truly are ready for us,” Principal Stephanie Tate said.

Many families took the scenic route to class so they could tour the new facility.

“Are you a fifth-grader?” asked teacher Allysia Cleveland as one child approached.

When the child nodded yes, Cleveland yelled, “Whoooo!!!,” sparking more of the same from the other fifth-grade teachers nearby.

London was the most animated. She danced, high-fived, took pictures, and otherwise entertained anyone walking by. Her room was decked out in clown-related and other fun decorations. It was related to the school’s theme for this year, “Under The Big Top.”

London said she bought all of it with her own money.

“I went all over — here to Houston, Covington, to Denham,” she said.

In the lobby, families spilled out of the main office, where during the first day the school added 41 students, ending the day with 723 students.

The school system as a whole had 43,420 students registered at almost 90 schools, 675 students more than were registered a year ago on the first day of the school year.

“Depending on where enrollment settles down, we’ll probably be able to hire some new teachers,” said Superintendent John Dilworth.

Some teachers also are likely to change schools to relieve schools with higher enrollment, a process known as “leveling,” Dilworth said.

Middle schools are particularly crowded, thanks in part to the Louisiana Department of Education takeover of four middle schools in the past three years.

Four Baton Rouge middle schools had about 1,000 students each Wednesday. Another school, Mayfair Middle, created in 2009, had 500 students, 40 more than its capacity.

School Board Vice President Tarvald Smith said Park Forest Middle, which had the most students, 1,061, will likely cross 1,100 in the days to come, putting it over its capacity.

“I can tell you that 200 of those students are from the Scotlandville area,” Smith said.

Not every school is full.

The Career Academy, a new charter school, still has some slots.

The new career-oriented high school is occupying the former Brookstown Elementary School, which closed in May. The academy had 175 students registered Monday. Two-thirds of those students, though, are ninth-graders while 47 are 10th-graders.

The school hopes to eventually educate some 100 students and grow outside of its current facility. The high school is focusing at first on just four career areas: health science; manufacturing; hospitality and tourism; and transportation, distribution and logistics.

Principal Pam Mackie, who last year ran Valley Park Alternative School, walked the halls of her new school alert for potential problems. At one point, she walked into an English class and noticed a boy with his head down.

“In this building, you keep your head up,” Mackie said sternly. “There is no sleeping here.”

For the school system as a whole, other problems were clear.

Several of the problems were connected to a rainy summer that delayed the completion of some construction work.

For instance, the school system’s transfer point is not yet repaved.

This week, instead, the school system is using Memorial Stadium near downtown Baton Rouge. Transportation Director Bill Talmadge said he was thankful that several City Police officers have volunteered to provide extra security at Memorial.

Dilworth acknowledged some delays in finishing up summer renovations at Howell Park, LaSalle and Melrose elementary schools, but said they are worth the wait and will be fixed soon.

“What we’re going to have is such an improved learning environment that by Labor Day people won’t remember the problems from before,” he said.

In most ways, the day went well, the superintendent said.

Schools were fully staffed, and all but one, Park Forest Middle, had a principal.

The School Board on Wednesday night promoted Curtis Walker from assistant principal at Broadmoor Middle to the job of interim principal at Park Forest Middle. LaMont Cole, the previous principal, has taken a job with a charter school in Baton Rouge.

Dilworth, however, noted that he has pressed his administrators to avoid other problems, including delays in getting students course schedules.

“We work very hard on master schedules over the summer, so that kids are not waiting in the auditorium or in the gym waiting on a schedule before they go to class,” Dilworth said.