In my opinion, James Loewen's purpose in writing "Lies My Teacher Told Me" was to get students/readers to think and ask questions of their teachers, leaders, government and themselves. I often ask my own students, "Why do people write history?" in order to start the thinking process.
I think we write history to preserve our view of an event. Have you ever met with childhood friends or siblings and recounted an event? Does everybody have the same story to tell about that event? Likely not. That is the point of this book. Historians write history to record events, yes, but from whose perspective? When we remember 9/11 will we remember it from the point of view of George W. Bush, a first responder, a victim, other government officials, the hijackers, or own experience? And whose agenda is served by writing and publishing, particularly in text books, a certain version of an event?
There is no short answers here, only more questions. Ask them and come up with your own answers. Find your own truth.