The Oxford is too brief and the McGraw-Hill Encyclopedia of Astronomy too detailed. The realities of teaching will ultimately dictate how far any instructor can go with the news-driven method. There probably is not enough time in the day for most professors, much less schoolteachers, to take a totally news-driven approach. But to continue teaching in a straight-line way will not prepare our students for their future in a chaotic world. As Hale-Bopp becomes brighter in the sky, it will afford an obvious opportunity to introduce astronomy in the news.
Comets are a stand-alone topic, requiring little preparation.
A discussion of comets could begin with an overall perspective on the contents of the solar system and how comets fit into that picture. The ASP's comets slide set comes with an excellent guide, and images of Hale-Bopp are already on the web. The techniques of observing the comet may also be expanded upon. Because comets are too large to view easily in a telescope, they can lead to a discussion of angular size and fields of view in telescopes and binoculars. Most students will probably have a hard time seeing the comet due to local light pollution, segueing into another entire topic.