This is certain: The first day of school this year at Lawrence High School won't be like last year's. Neither will the last day, wherever the students are going to class.

On Tuesday, school will begin at Lawrence High in what Superintendent Wilfredo T. Laboy is calling ``a year in transition."

There will be six new principals, double sessions, a developing curriculum, and uncertainty when everyone will move into the yet-to-be-completed new high school in South Lawrence. The moves -- some temporary, others permanent -- are all part of an effort to reshape the city's high school experience and to close the achievement gap with other communities.

``We have a lot of challenges this year, but we are ready," said interim principal Albert ``Duffy" Miller.

The six new principals will oversee six new schools that Lawrence High established so that students can graduate with a more focused educational experience. Though the full program won't begin until next year, Miller said, students may take part in pilot programs this year, while principals and teachers lay the foundation for one of the most radical curriculum changes in the school's history.

Eventually, incoming students will have a choice between the Humanities School; Business School; International School; Health & Human Services School; Performing & Fine Arts School; and Math, Science & Technology School. There also will be a principal overseeing the entire school.

Laboy said the change is needed because the days of the one-stop, comprehensive high school are over.

``We have to start thinking in new terms to prepare these kids for a new world," he said. ``The comprehensive high school model just doesn't work anymore."

The smaller schools will allow teachers to better keep track of students and record their progress, Laboy said. He also said that since unveiling the plan for the new schools, parent involvement in the high school ``has increased substantially."

Among the new principals recently hired is Dianne D. Cruz, a graduate of Lawrence High. An engineer by training, Cruz will lead the Math, Science & Technology School. ``This is the community I serve; this is the community I want to serve," Cruz said. ``There is no other place I want to be but in Lawrence."

The curriculum for the schools and just how it will be integrated is still being worked out, Miller said. By next school year, he said, things should be much clearer.

``We're flying the plane, but we're also building it at the same time," Miller said. ``Everyone is on a learning curve this year."

For Lawrence students, the stakes are high. Close to 90 percent of the student body is Latino, and the school is one of the most overcrowded in the state. Nearly 75 percent of Lawrence High students come from low-income families.

The school also has some of the lowest state test scores in the state. In 2005, for example, only 30 percent of sophomores scored proficient on the state's reading test, and 25 percent scored at that level in math. Still, those scores are better than in 2002 and have shown steady growth, according to schoolmatters.com, an education website run by Standard & Poor's.

Cruz acknowledged that when she sees those past test scores, she feels some pressure. But she also thinks that things will improve. ``When we make math alive, those test scores will go up," she said.

To battle overcrowding, Lawrence freshman will be required to go to school almost three hours after other students, to make room at the old campus until students and teachers can move into the new building.

The downtown campus originally was built to house around 2,000 students; the current enrollment is nearly 2,900, making it one of the most overcrowded schools in the Commonwealth.

The double-session plan has drawn fire from the teachers union, which argues that it will disrupt family schedules.

When the move to the new school will take place is still anybody's guess. The $110 million project hit another delay last month when a contractor walked off the job because of financial problems.

Laboy hasn't set a date for the move, but said the double-session plan is a temporary fix. ``Just look at what's at the end of a tunnel," he said. ``That's what's important."

Russell Contreras can be reached at rcontreras@globe.com.

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