The Grade Distribution visualizes the distribution of the participants' letter grades in the grades overview. Changes to letter grades can be visually analysed, saved and overwritten if necessary.
To prevent potential collisions, it might be a good idea to use better namespacing in the $SESSION object. Instead of $SESSION->gradeitem something like $SESSION->gradereport_gradedist_gradeitem or $SESSION->gradereport_gradedist->gradeitem might be safer.
Additionally, I believe you do not need to do global $SESSION in scripts like index.php as they are executed in the global context implicitly (unless I miss something).
To prevent potential collisions, it might be a good idea to use better namespacing in the $SESSION object. Instead of
$SESSION->gradeitem
something like$SESSION->gradereport_gradedist_gradeitem
or$SESSION->gradereport_gradedist->gradeitem
might be safer.Additionally, I believe you do not need to do
global $SESSION
in scripts like index.php as they are executed in the global context implicitly (unless I miss something).