"When I first learned that a commercial airliner had crashed into the World Trade Center, I thought it was some kind of horrific accident. When the second plane struck the South Tower, and a third hit the Pentagon, I knew the United States was under attack. As we reflect on 9/11, our temptation will be to recall the horrors of that morning wrought by violent extremists who targeted symbols of America's strength and prosperity in an effort to wage war on the very ideals that make our democracy thrive. Indeed, we must never forget the innocent Americans who perished in those devastating attacks or the pain that these victims' families continue to suffer. We must remain vigilant in the face of a persistent and very real threat. The terrorists have to be right only once—we must be right 100 percent of the time. It is a challenge, nonetheless, that we must meet. Yet the most enduring legacy of that day lies not in the tears we shed or the lasting threat that we face but the small acts of ordinary citizens whose courage and compassion revealed the resilience of the American spirit. It lies with the police and firefighters who rushed into smoldering buildings with little regard for their own safety and rescued their fellow citizens trapped inside. It lies with the women who accompanied their Muslim neighbors to grocery stores in the days after the attacks to protect them from violent reprisals. It lies with the passengers of United Flight 93 who fought down their hijackers and made the ultimate sacrifice to save hundreds of American lives. It lies with the men and women in uniform who day after day fight on the front lines defending freedom across the globe. September 11 will endure in our memory because, even as our nation confronted its worst fear, the strength of America's spirit and its everlasting commitment to freedom and democracy triumphed." Condoleezza Rice

This unit -- We Have Some Planes -- asks students to return to September 11, 2001 and recount the day's events. When did the attacks on the World Trade Center, the Pentagon, and Washington D.C. begin? Who were the al-Qaeda operatives that participated in the attacks? And, how did Americans respond? The answers to these questions are critical if we are to understand the intent and capabilities of the terrorists and the swift and overwhelming response of the United States.