Hi Ivica,
your need to let your teacher use shared course material uploaded from an admin ? In that case you may want to explore repositories. One repository that could suit your need is Filesystem repository where an authorized users can
upload content file (for example via
FTP), then content file can be used from teacher in their course from within Moodle using File picker:
http://docs.moodle.org/24/en/File_system_repository.
According to your requirement you may need to tweak roles to regulate repository visibility.