The speaker can convey personal enthusiasm in a way that no book or other media can. Enthusiasm stimulates interest, and interested, stimulated people tend to learn more. Lectures in university settings can provide students with role models of scholars in action. The professor's way of approaching knowledge can be demonstrated for students to emulate. Lectures can convey material otherwise unavailable, including original research or recent developments that have not yet made it to publication.
Lectures can organize material in a special way.
They may provide a faster, simpler method of presenting information to an audience with its own special needs. Lectures are particularly useful for students who read poorly or who are unable to organize print material. Lectures can convey large amounts of factual material. Lectures can speak to many listeners at the same time. Lectures permit maximum teacher control.