Because she thought Kyron was still in the school?
I said I was going to look at other exhibits - how do you mess that up? His coat and backpack were still at school.
-TH June 5 email-
The teacher may have took roll call between 8:45AM and 9:00AM but didn't mark Kyron absent at this point because she had seen him with Terri in her class and Terri had told her they were going to look at other exhibits. The teacher assumes Kyron's going to return. She doesn't hold up the student tour, Kyron can join it in progress. The teacher assigns students to chaperones. (no need for head counts because she already took roll call)
The tour begins without Kyron. The teacher has an hour to kill before the students return. She forgets about Kyron. At 10:00AM the students return. Now the chaperones do their head counts.
Chaperone: Oh no, where's Kyron there's only five!
Teacher: Don't panic, he's probably in the bathroom or getting a drink of water.
At this point the teacher is still thinking (hoping) Kyron did join the tour at some point and has now wandered off somewhere. She does a quick search but no Kyron. Now the idea of a Dr.'s appointment comes into play.
But the question remains: If the teacher was confused about Kyron's whereabouts, why wouldn't she notify the front office? And if she did, why didn't the school contact any of the parents? If Kyron was not present during roll call, then the teacher and school may have decided that Kyron's whereabouts wasn't their responsibility(despite the fact he was seen earlier in class).
I hope that isn't the case.