If Bush did sit through another 25 minutes in the classroom, I cannot believe he did so without Card having told him that everyone who could be gathering information was gathering information and that there would be a report coming soon, at which time Bush would have removed himself immediately. He would not have ranked a school visit above national security, no matter what detractors say, imply, or insinuate.
There may have been 25 minutes between Bush being told about the plane #1 and #2. He did not sit there reading stories to the kids for 25 minutes after being told of the second attack. He made a short statement to the teachers present about what happened and then when the secret service was certain that it was safe to move him, the President was taken to Air Force One where he could be better protected against the terrorists that were attacking the country. His staff you can be sure was collecting information for him. During the first few minutes, you know you cant really be sure about much of what is offered up as intelligence.