Teaching large groups is often synonymous with the lecture format.

For those new to lecturing, this book "What's the use of Lectures?" by Donald Bligh, which is available via http://www.netlibrary.com pulls together the implications of research on both the physiological and psychological effects of the lecture and provides ideas and guidance for making the most of this way of supporting student learning.

This website contains useful ideas about Promoting Enhanced Student Learning (PESL) and below is the link to the section on working with large groups in a variety of ways other than the lecture format:

http://www.nottingham.ac.uk/teaching/resources/methods/largegroup/

One key issue with the lecture format is the voice and the strain that lecturing can place on the vocal chords.  A Continuing Professional Development workshop took place in both Michaelmas and Lent terms 2008/9 entitled "Supporting your Voice: cultivating awareness and healthy practices " - the handout from this workshop provides useful tips and guidance as well as links to further resources to help you in maintaining a healthy voice.  The PowerPoint slides from the session are also available here .