I've been considering producing my own commercial training materials, and would like to get a better idea of what medium most people prefer to use. In the poll here I've listed the four methods I think are most common.
Text books - Includes any study guides or reference material in dead-tree format.
Self-paced videos - Prerecorded videos of training presentations (assume this covers audio-only recordings as well).
Virtual classroom - Live classes held virtually.
Physical classroom - Live classes held at a physical location.
If you have another you'd like to add please mention it in the comments below. Note that I'm only looking for actual training materials here; it is assumed that, like any networker worth his paycheck, you're labbing out whatever you're studying as well.