I believe it should show up as "ACO" Academic Out of the building ... "ACI" is Academic In the building -- like if they were pulled for a small group assembly or something. Not sure if that's what parents see though?

Yes, any time they are not sitting in the classroom, they are technically counted (or should be counted) as absent. It's excused. The code for Outdoor Ed is something like "School Field Trip".

Yes excused absences. The teachers at outdoor ed won't call the school and tell them that the kids are accounted for. The attendance secretary will get a list before the group leaves and will input the absences

Did outdoor ed count as absences for sixth graders? Is that correct?