From what I have seen on the census, if they came to a boarding house, resident school etc, they would list the people actually there. I have seen them even list someone who was just visiting as a member of the household as well. Guess it just depended on what the census taker wanted to do and they many times did as they saw fit. I do not have info on the school year calendar for AMI. I thought I remember it being ran much like West Point and VMI as a resident school. As in those, they gave the summer months off if my memory serves me, so true, the boys would not be in school probably at the time of the 1860 census. So if that was the case many would have been home in 1861 when Co I 3rd Ark was mustered in to service and not in Tulip to join that unit...if in fact the school still existed as such.