About 100 students and parents from Silver Spring International Middle School rallied Tuesday morning in hopes of preventing scheduling changes they say could hurt student achievement.

The school is planning to go from an eight-period to a seven-period schedule starting the 2014-15 academic year.

But eliminating the eighth period of classes will limit students’ chances to receive additional academic help in a subject they’re struggling in or take an additional elective, said Margy O’Herron, a parent who organized “Rally to #Savethe8.” Parents are also worried about how the changes would impact the achievement gap, possibly negatively impacting minority students.

The schedule change would not affect the length of the school day.

Parents say since the school started an eight-period schedule about seven years ago, student achievement for poor and minority students has surged. Many of Montgomery County’s middle schools have a seven-class schedule.

The school “has overcome significant challenges and the eight-period schedule was a key part of the formula for success,” according to an appeal from parents.

Principal John Haas denied the appeal in May.

“Even though a schedule structure can impact student achievement, the most impact by far comes from day-to-day instruction that the students receive from highly qualified educators within any schedule structure,” Haas wrote in a May letter denying the appeal.

Tom Israel, executive director of the Montgomery County Education Association, said some teachers at the school had concerns about the eight-period schedule, saying providing the additional elective takes away from the instructional time students get in core subjects such as English, math, science and social studies. And because the periods alternate days, some teachers are worried that the current schedule disrupts the continuity of instruction. Teachers may go several days without seeing students if there are holidays, emergency closings or other events, Israel said.

Superintendent Joshua P. Starr and his staff will review the parents’ appeal.