More than 500 Scripps Ranch High School students had their summer vacations disrupted Friday with news that they would have to return to school to retake Advanced Placement tests that have been declared invalid.

The College Board, the organization that oversees college admission tests, did not claim any students cheated on the exams, but is invalidating 847 AP tests because new seating arrangements established two years ago were not followed. The move means 540 students will have to take the tests again.