Wikimedia
Wikipedia: Korean War
This encyclopedia article from Wikipedia provides a thorough discussion of the Korean War, the 1950s conflict between communist North Korea and anti-communist South Korea.
Annenberg Foundation
Annenberg Learner: Primary Sources: Korea and the Cold War: A Case Study
An hour-long professional development workshop on teaching the Korean War and containment with primary sources. Features experienced teachers. Materials and a complete lesson plan are also available.
BBC
Bbc: The Cold War: The Korean War: An Overview
The BBC provides a detailed 5 page overview of the Korean War that took place in the mid-1950s.