I've lurked on the site for quite a while and this is my first post... I've been following this thread since poor Kyron disappeared last week. I have a few thoughts I'd like to toss into the mix:
1) LE won't discuss Kyron's medical conditions (or lack of)... But what if he does have a medical condition that requires him to have lots of appts and miss school regularly? Let's say Kyron's teacher saw Kyron and Terri at the science fair. School wasn't even in session, yet. When classes started, the teacher may have thought that Kyron and Terri dropped off Kyron's project, toured the science fair, and left for an appt. Teacher would have marked Kyron absent and not been startled by the fact that Kyron's backpack and project were in the school. I've seen parents and students do this throughout my children's school years. They'll go to an event before school, go to an appt, and come back later in the day. Also, if Kyron has lots of appts throughout the school year, the teacher might not have thought it unusual if one 'ran long' or lasted all day.
2) Speaking of marking absences. LE confirms that Kyron was seen around 9 AM. The science fair was scheduled from 8 to 10 AM (
http://www.kptv.com/slideshow/news/23802076/detail.html) so it seems that school didn't start till 10 AM. What did the kids do during that time? I'm sure they viewed the science projects, but did they go outside and play on the playground? Mingle inside till time for class? If children were going back and forth between the playground and the school then there were plenty of opportunities for Kyon to be outside the school. Classes started at 10, which would have been when Kyron would have been marked absent (unless there's another Kyron sighting later in the day that LE is not speaking about).
3) Even the best kid gets caught up in all the excitement of a day that's not part of the normal routine. The science fair day was not a normal day at school. The kids would have been excited, classes were not starting till later, and there would have been lots of socializing. What if Kyron decided to walk near the woods looking for whatever a 7 year old boy may want to look for? What if he walked in a little ways, stooped to pick something up and his glasses fell off? Now he's in a situation where he's surrounded by dense green vegetation and he can't find his glasses... Does he keep looking for them and get disoriented? Start walking the direction of the school (or what he thinks is the direction of the school) and go further into the forest and get lost? I know this sounds farfetched, but the photos of the terrain show how easy it would be to get lost, especially for someone as young as 7.
4) LE stated that Kyron was last seen near the South entrance of the school
http://www.oregonlive.com/portland/index.ssf/2010/06/still_no_trace_of_kyron_horman.html
It's not been stated whether he was inside the building or outside the building. I tend to think that whatever happened to Kyron happened outside the school. If LE thought something happened in the school and they needed to collect evidence of it, then they could have very easily shut the school down for the last few weeks of school.
5) My stomach turns as I type this last part, but I can't help but think of poor Adam Walsh... He wasn't stalked and there was no plan, he just happened to walk out of a mall and into the arms of some sicko.... I hope and pray this isn't the case with Kyron, but with such an unusual schedule for a school day it would be very, very easy for a predator to see an ideal opportunity, come up with an impromptu plan, and grab little Kyron. I hope and pray this is not the case... I hope and pray he's found right now...