With modern recording devices, a reminder that your classes are not really private, whatever the legalities

That was then and this is now.

We have reminded faculty from time to time that emails and other communications at public universities are generally not private and can be requested as public documents.  There are some questions about the legalities of students recording your classes.  A recent case in which a teacher in the LA school district was recorded cursing - and was suspended - is a reminder, however, that once a recording goes public, it can't be retrieved.  Moreover, it is very unlikely that a student will be prosecuted for making such a recording.  And recording via cellphone or other small device is now very easy.  The LA Daily News has an article triggered by the cursing teacher example:

Under California Education Code Section 51512, it... is illegal for any person — including a student — to use an electronic device to record what is happening in the classroom without the consent of the teacher. But here is where the matter gets tricky: The teeth in the law really applies only to people who are not students. That is, any non-pupil who is caught recording a classroom discussion without the teacher’s consent can be charged with a misdemeanor.

“If I want to audit my kid’s class — maybe I think the material violates some religious belief — I can’t record the class without the teacher’s permission," said Rebecca Lonergan, an assistant professor of law at USC. When it comes to students who are caught surreptitiously recording their teachers, the punishment is determined by school administrators. “If it’s a student, you’re not going to criminally prosecute them for recording their teacher,” said Lonergan, who also has worked with the U.S. Attorney’s Office, where she dealt with many wiretapping cases...

Full story at http://www.dailynews.com/social-affairs/20131012/case-of-cursing-lausd-teacher-raises-legal-questions-about-secret-recordings

Of course, you can ask students not to record your class or only to record it if you give permission.  But that request doesn't guarantee anything, as a practical matter.