many to many relationship between dimension level

I need help to design dimension model. Detail of Dimension are as following:
Dimension : Student, School
Fact : Grade

1. Class_Year
2. School
3. Area
4. City
Analysis Requirement are to drill up /down by above given hierarchy

there is :
M:1 relationship between Area and City
M:1 relationship between School and Area.

Issue : there is M:N relationship between Class_year and School. Every school have class year 6,7 and 8 and vice versa.

fact table consist of grade of students.

I have designed dimension Student as stud_id/name,address etc.
Dimension School as school_id / name, Class_year / Area_code / City.

but in BO reporting, Drill down/up is not working properly, reason may be Many to Many relationship between Class_year and School_id.

Could you please help me to design dimension tables, Do I need to split dimension 'school' into number of dimensions, if yes how.

Regards

Take class year out of the school dimension. Make it its own dimension, or if there are no attributes, create a degenerate dimension.

School, area and city are (unless there is a major earthquake) static highly correlated geographic attributes, while year is not. Combining uncorrelated attributes into a single dimension can cause problems.

thanks !
Class_year does not have any other attributes, Is there any disadvantage if I create separate dimension rather then degenerate dimension. Description can be added to Class year.

regards

If you add a description, then it has attributes, so it cannot be a degenerate dimension. Even if there are no descriptions now, if there is a potential to add them in the future, you should create a proper dimension table.