Math and/or Physics courses would probably have equations/forumlas and use a Math editor to build. Those get converted into images.
Suggest downloading a backup (.mbz). Change the backup extension from .mbz to .zip and unzip into a work folder. Inspect the contents of the extracted backup. The xml files are pointers to all things in the backups - folders extracted and the files contained there in are in course_files by content hash names.
Unfortunately, there is no GUI Admin user interface into the new file system. One has to use DB queries to find humanly recognizable file names to see the content hash assigned to the file and then a file browser of some sort to browse the directories of moodledata/filedir/ to find the content hashed named files.
Might shed some light:
http://docs.moodle.org/26/en/Course_files
'spirit of sharing', Ken