Conversion of statements to E-R Diagram EDIT: PLEASE DON'T CONSIDER ARROWS :)

statements are

"A teacher can teach many courses. A student 
can enrol in many courses. A course may 
be a part of one or many programmes. A 
teacher can be mentor of many students, 
however a student can have only one 
mentor."

Having confusion is Mentor an entity or not

I have drawn two E-R diagrams with



and without mentor



this diagram can be accessed here
is Mentor of is a relationship between a teacher and a student.
From your diagram I conclude that a course can be only be enroled by one student. I is not explicitely stated but I think that a course can be enroled by many students. Also I think that a course can be part of more then one program. Finally I get the following diagram:



The diagram is created with dia and the source can be found here. 

In the diagram all relationships are defined mandatatory. So the the diagram should be refined in respect to this. For example it seems to be wrong that each teacher is mentor of at least one student.