I am having a problem with students home directories

the path to their home directories looks like this
\\servername\students\sc\username

the actual share is students

For some reason the students are able to write on the
students share and all other folders on that share

share permissions for students share: students group read
and change

security permissions- read and execute fot the students
group and then their user account just has their username
with write priveleges

Now if I take the change permission out of the student
share the can't write to their home directory but if I
leave it in they can right everywhere