Paul Mayer's U.S. Government class at Hanford High sat motionless in first period Thursday. The teenagers silently stared at a screen.
Then the students gasped. Hands flew up to faces. The silence in the room grew tense.
Clearly visible on the screen, people plunged to their deaths from the upper floors of the burning towers.
The students were watching 102 Minutes That Changed America, a documentary assembled mostly from amateur video footage taken in lower Manhattan on Sept. 11, 2001.
At the start of class, Mayer told his students that they wouldn't have to take notes during the film. "I just want you to get a feel for what was going on that day in New York," he said. "And on Sunday, I want you to think about it, at least for 10 seconds."
Most students in the Tri-Cities studied the events of Sept. 11 this week. Depending on their ages, they might delve deep into the tragic event and its aftermath or only learn the basic facts.
Some teachers focus on 9/11 this week, some cover it as it fits into the timeline of their course.
But all agree that important lessons can be learned from the day that still reverberates in Americans' daily lives.
A life-changing event
The students at Hanford High sat mesmerized through the first half of 102 Minutes on Thursday. The senior class had seen many of the individual images during the years, but several said after class that they never had seen video footage and never gotten such a complete look at how New Yorkers experienced that morning.
"I didn't know people jumped out of the buildings," said Aaron Tansy, 17. "When you're 7, you don't take things in the same way we do now."
The seniors were in second grade when the towers fell. They have spent almost their entire school careers with annual moments of silence for the victims of a terrorist attack the extent of which they fully are grasping only now.
But they always knew that the disastrous attack happened very unexpectedly, and that has stayed with them.
"It's life-changing to know that pretty much at any second somebody could do something like this," said Dylan DeRosa, 17.
Sadie McDermott, 17, said that the video footage reawakened her fear of "the terrible things people do."
All three, however, agreed that the film pulled together all the bits and pieces they had learned during the years about the attacks and put the textbook information into context.
They also said that on Sunday, they would think about the people who died.
That is one part of what Mayer, their teacher, hoped to achieve. He will bring up different aspects of 9/11 throughout the whole semester -- the wars in Afghanistan and Iraq, the loss of some individual freedoms and the formation of the Department of Homeland Security, for example.
But every year, in the days leading up to the anniversary, he wants to do "his little part to help them remember," Mayer said. He handed out sheets with 9/11 statistics before the film, including the number of people killed in the attacks.
With his freshman U.S. history class, Mayer goes into much less depth and avoids all gruesome images, he said. He explains to them that there were four hijacked planes and that people died, and then waits for their questions.
Some of the younger students ask him the most complex question about the tragedy -- why did it happen?
"I don't know whether I ever fully answer that," Mayer said with a sigh.
As old as 9/11
Kelly Williamson teaches reading and writing to every fifth-grader at Finley Elementary. Kids, most of them born the same year as the attacks, cycle through her room all day.
On Friday, Williamson changed up the curriculum. She read books about 9/11 to the kids, shared photos she took at ground zero in 2003 and showed them video clips of the day's events, making sure to stop the clips before any gruesome footage.
Some kids knew nothing about the event at all -- barely knew that it had happened, Williamson said. She had to start from scratch, explaining that four planes had been hijacked and used to destroy many human lives 10 years ago.
She explained to the kids what terrorism is and how the country pulled together in the aftermath of the attacks to rebuild.
Williamson will continue the theme into the next week to talk about the heroes of that day, she said.
After the kids had watched videos, looked at photos and listened to stories, Williamson asked them to express what they felt in a writing assignment.
On Friday afternoon she hadn't had a chance to fully read everything the kids had written, but what she had seen told her most of them felt sad about what they had learned.
Teaching 9/11 to adults in college courses has advantages and challenges, said Robert Bauman, a history professor at Washington State University Tri-Cities in Richland.
It's easier than teaching, say, the Civil War, because more students are interested in learning about an event that is embedded in their own memory.
But that also makes it harder, because most students feel they already know a lot about this chapter in history.
It's important to have "a completely open classroom," where students can express their opinions, Bauman said. That can mean opening the door to far-fetched conspiracy theories, which Bauman tries to address without making the student "feel stupid," he said.
"I just ask them for evidence to support (the theory)," he said. "I'm not trying to change anyone's mind."
Mostly, Bauman asks questions, he said. He asks students what they remember from that day and why they think it happened. And he puts the event in perspective, listing previous domestic terrorist acts.
"The history of terrorism in the U.S. is not connected to any one particular religion," Bauman said. "It's about politics."
Bauman, for the past two years, has taught a U.S. history survey course, which gives students an overview of historic events, without going into depth on any one.
Instructors in survey courses often run out of time at the end of the semester before they get to the most recent events, but students taking Bauman's class always learn about 9/11.
"I make sure I get that in," he said.
Not every educator is in favor of paying special attention in school to the anniversary of the attacks.
"I don't advocate for doing a whole lot," said Arlene Jones, principal of Tri-Cities Prep, a private, Catholic high school in Pasco. She formerly was in charge of social studies curriculum for the Pasco School District.
Her aversion to special 9/11 classroom activities in part stems from personal experience. Jones' daughter was born Sept. 11, a few years after the attacks.
Every year of her life, the girl has had to listen to taunts about her birth date from other kids, Jones said. "She's told me, 'The terrorists stole my birthday,' " Jones said. "To a mother, that's heartbreaking."
Jones is not suggesting the historic event shouldn't be covered in class, far from it.
"We need to learn the lessons of 9/11 and make them real for our students every day," she said.
That means teaching tolerance, teaching how we are different from terrorists and teaching world religion, Jones said.
"If the only time we teach 9/11 is on 9/11, we really miss the mark," she said.