On today's lesson: How do people receive security clearance to see secret, or top secret government material? Who grants it, and how is that clearance revoked in cases of misuse?  Do people with security clearance have unfettered access to secret material, or is classified information compartmentalized? Also, does the President have any restrictions to his security clearance? Today's guest is Juliette Kayyem, national security analyst for CNN and Boston Public Radio, and host of the podcast The Scif.