Everything you need to understand or teach The Johnstown Flood by David McCullough.
The Johnstown Flood describes how on May 31, 1889, the earthen dam holding back Lake Conemaugh 15 miles upriver from Johnstown, PA, gives way in abnormally heavy spring rains, and a wall of water races down the valley, scraping away all trace of several small communities before destroying and drowning the populace of Johnstown in ten minutes. Relief operations begin immediately, involving the American Red Cross, and locals try unsuccessfully to blame a club...
The Johnstown Flood Lesson Plans contain 136 pages of teaching material, including: