Hello everyone

I am an IT student from Greece and i would like your help regarding a Data Base exercise.
I would be greatful if you could guide me to clarify some points


The Data Base Case is the following:

The DB maintains historical information (for all the school years)
for each school unit, for the total of elements that are presented
below:

• the elements of region where the school unit belongs are
  registered with the following form: <district,province,
  municipality, municipal department, area>
  
• the further elements that are stored for each school unit
  are the < name, SUcode, Telephone, fax, email, postal address,
  elements of the director (the director of unit is a schoolperson
  with exclusively organic place in the unit).
  
• for each schoolperson the data base maintains the
  <SPcode, name, surname, mother’s name, father’s name,
  specialty, and SSN>.
  Also is maintained the information of the
  organic place of the schoolperson (each schoolperson belongs in
  only one school unit "organically".......) as well as the
  information of all school units that the schoolperson are occupied
  (...while they could be occupied in more than one unit, with
  hours (per week) that should be working in his organic school
  unit. If for some reason this hours aren't covered , then the
  schoolperson could be able to be disposed or detached to another
  school unit, with obligation of occupation of certain additional
  hours.
  
• The DB maintains elements of students (one unique code,
  name, surname, mother’s name, father’s name), the class where
  they belong to in each school year, the elements of their school
  unit and the final degree in all the courses, per school
  year.

My question is how to draw in an ER Diagram the realation between the
schoolperson an the school unit so the DB can keep both the
information of the organic place of a schoolperson and the
information of the school unit he/she is disposed or detached and
the relative hours

Thank you in advance

Hmmm. Sounds as if there may be a many-to-many relationship between school person and school unit?

How can there be many-many relation between school unit and school person?

One school unit has one school person allocated organically
One school person can be allocated to other school unit if his hours are remaining

I tried an ERD for the requirement, can anyone please tell me how far Iam correct!!