Thirty three Central Florida elementary schools must extend their day by an hour when school starts next month, a plan some say will boost reading skills but others fear will leave young students sapped and overworked.

The 33 schools — on campuses from Leesburg to Orlando to Sanford — landed on the state's list of lowest-performing elementary schools because so many of their students did poorly on Florida's reading tests this spring.

Now they must provide an extra hour of daily reading instruction for the 2014-15 school year, tacking it on to a typical six-hour school day.

"I strongly disagree with it", say Carta Fischer whose 10-year-old daughter attends Orlando's Fern Creek Elementary School, one of 23 campuses in Orange County on the list.

Fischer said she worried a longer day would leave her daughter too tired for after-school karate classes and limit teachers' ability to offer enrichment programs before and after classes.

  Her daughter is a strong reader, she added, but even youngsters who need extra help might feel burned out because they already spend so much time in class, with little or no recess.

Lawmakers required the extended day to give struggling students an extra dose of needed reading lessons, and that makes sense to Oscar Aguirre, principal of Lovell Elementary School in Apopka, which is also on the state list.

"I'm very, very happy about getting that extra hour," he said.

Aguirre was planning to schedule before or after-school tutoring for his students, many of whom are still learning English and struggle with reading comprehension. But assuring attendance at tutoring sessions can be tricky.

With the new schedule — and school-bus service to accommodate it — students will get extra reading help during their school day. That, Aguirre said, "is a positive thing."

The extra hour is mandatory for all students except those who scored a 5 on the reading section of the Florida Comprehensive Assessment Test, the highest possible mark on the five-level exam. Those students could skip the extra hour. A 3 is considered passing but would not exempt students from a longer day.