Domain\Classroom\Classroom::students PHP Method

    public function students()
    {
        return $this->belongsToMany(Student::class);
    }

 /**
  * Associate students.
  * @param  Classroom $classroom
  * @param  array     $students
  */
 public function associateStudents(Classroom $classroom, array $students)
 {
     $ids = [];
     foreach ($students['students'] as $student) {
         $ids[] = $student['id'];
     }
     $classroom->students()->sync($ids);
 }