Hide article but not its menu item - Joomla! Forum - community, help and support

okay, here goes. i've been trying work out afternoon. no luck far. looked everywhere , anywhere work out... i've followed guide:

http://magazine.joomla.org/issues/issue-feb-2012/item/639-joomla-acl-access-levels

coincidentally... school site!!!

i've created 2 new user groups: teachers , students.

then assigned core permissions , went on created users assigning them relative groups. next step making actual access level. fine here. in guide.

at point went straight articles (three of them) want logged-in users able see (teachers). don't want public or students (who can log in frontend) see these 3 articles, but want them aware article exists - that's why left menu item set "public", can see menu item in frontend.

this happens:

everyone can see menu item, when click on item takes article tells you don't have priviliges see article. perfect far...

the problem can log in can view articles, whether teachers, students or "registered". want teachers see articles - others supposed "you not authorised... bladiblah..."

if set access level "teachers" menu item, hides menu item public , students... don't want hide menu item...

for want know why don't want hide menu item: problem of users won't register until aware of limited access of content... teachers, is. if see menu item, find limited access, should "wake them up"... students, on other hand, register access other features, shouldn't allowed see teachers can see.

i'm running joomla 2.5.8.

any appreciated...

hate ask .... doesn't have idea me???