You may have had the experience I've had on the Acropolis of talking to your group of students, on their wavelength, only to be interrupted by an official guide who tells you it's illegal to do your own guiding. You, having studied the buildings with your students, will make a much more effective guide for them, but you can't do it.
Perhaps the answer is the mp3 player.
This Guardian piece tells you how to download auido guides to various walks in the UK, to listen to on your mp3 player.
As far as I know, there are no audio guides to the Acropolis on line yet, but you could make your own, just recording what you would say at each spot if you were allowed to. If students don't have a player, they might borrow one for the trip. You wouldn't have to include instructions about where to go next, because no one will stop you shepherding your party from the caryatid porch to Athena's olive tree.
If you make such an audio guide and would be prepared to share it, then I'd be glad to set it up as a podcast for others to download.