St. Paul Public Schools has announced it will proceed with plans to make high school start times an hour later beginning in 2019-20 to better align school starts with teenage body rhythms.

The lone exception will be Washington Technology Magnet School, where students now attend school an additional hour per day.

The change to 8:30 a.m. start times for high schoolers was set in motion by the school board last October. A big question, however, was how the district would handle a related move that had generated controversy — that being a proposed shift of 10,000-plus elementary students to earlier 7:30 a.m. starts.

The start times schedule released this week shows all but three of the elementary schools now with 8:30 a.m. starts moving to 7:30 a.m. starts in 2019-20. Bruce F. Vento Elementary, Capitol Hill Gifted and Talented Magnet, and Riverview West Side School of Excellence will shift an hour later to 9:30 a.m.

"We understand there will be significant challenges for some families," the district acknowledged on its website. Committees are working to ease concerns involving child-care options before and after school, scheduling of sports activities and the safety of elementary students going to school earlier in the morning, officials said.

Parents and others have noted that many school bus waits during the winter could occur in darkness.

Recent discussions over start time changes in St. Paul go back to 2014, when administrators and board members said they wanted to seize on national and local research showing that high school students can benefit emotionally and academically when they get more sleep.

A study on the impact of later starts in the South Washington County School District found performance on state standardized math tests rising and the total number of crashes involving 16- to 18-year-old drivers in Cottage Grove and Woodbury dropping by 6 percent during the year under review. About 59 percent of high school students surveyed said they were averaging eight or more hours of sleep.

In St. Paul, transportation was a key component of the start-time equation, and Metro Transit — the go-to for high school students in Minneapolis — lacked the capacity to expand service to students in St. Paul other than those at Johnson Senior High and Creative Arts Secondary School.

The district and its yellow bus system had to retain a three-tier schedule of 7:30 a.m., 8:30 a.m. and 9:30 a.m. school starts, and that meant some of its youngest students would have to move into the unappealing 7:30 a.m. slot. In addition to agreeing to move to later starts for high schools, and to delay that action until 2019-20, the board also decided last fall that it would not require elementary students who now have 9:30 a.m. starts to move to 7:30 a.m.

Toya Stewart Downey, a district spokeswoman, said Thursday that Capitol Hill, a grades 1-8 school, was being moved from 8:30 a.m. to 9:30 a.m., and not 7:30 a.m., so its older kids could begin school later. Bruce Vento and Riverview elementary schools were being moved to 9:30 a.m. instead of 7:30 a.m. to ensure that families in their respective areas could have both 7:30 and 9:30 community school options for their children, she added.

Washington Technology Magnet will retain its 7:30 a.m. to 3 p.m. extended day schedule, which is fine with Karen Casper, who teaches Advanced Placement biology. She noted Thursday that many students there take College in the Schools advanced courses during the extra hour they have in their school day.