Professor John Dinges is in charge of the radio journalism curriculum at Columbia Journalism School. He was the managing editor for news at NPR for 11 years, where he witnessed, and contributed to, the remarkable evolution of US public radio. For World Radio Day, Professor Dinges gives us an insider's account of the impact of radio journalism, and the role of public radio in the age of the Internet. We also spoke to Caitlin Sanders, who currently works for NPR, on her discovery of the unique power of public radio.