They are a means of discussing issues related to a specific topic in a public forum, not a private one. Unlike email, a newsgroup posting is available to anyone on the Internet, and certainly is viewable by anyone accessing that newsgroup.
Postings usually have a time limit, after which they are removed, or archived separately.
However, the newsgroups can only be viewed convienently on computers where the user has the software configured. Virginia PEN has a server which teachers are free to use when setting up Netscape or MS Explorer. It offers a very wide variety of educational newsgroups. See this page for directions on addressing the PEN newsgroup server. Directions for setting up Virginia PEN's newsgroup server at your computer are available here.