my @classrooms;
my %classroom = 
(
  classroomID =>'$',                      
  classroomName=>'$',   
  students=> \%student,
);

my %student = 
(
  studentName => '$',             
  studentSurname=> '$',
  studentID=>   '$',
  age=>  '$',
);

##</code><code>##

    my $student = ( studentName => 'John', studentSurname=>'Something',  studentID=>'9534', age=>'12' );
    my $student = ( studentName => 'Mary' ,studentSurname=>'Something2',  studentID=>'5489', age=>'13' );
    my %classroom = (classroomID => 10, classroomName=>'classroom1');
 
##</code><code>##

 $classrooms[0]->students[0]->studentName