sub select_your_school {
    my $namesref = shift;

    # create a list of sorted hash keys
    my @menuitems = sort keys %$namesref;

    print $q->header,
          $q->start_html(-title=> 'Select Your School'),
          "Please select your school from the following list:",
          $q->start_form,
          $q->popup_menu( {-name =>    'school_id',
                           -values =>  \@menuitems ,
                          }),
          ....