Armour High School is the only high school in Armour, South Dakota. It is the only high school in Armour School District 21-1, which also includes an elementary and a middle school. Armour High School's athletic teams were formerly nicknamed the "Packers" and played in Class B of the South Dakota High School Activities Association.
Armour, South Dakota only has one middle school.
It's not explicitly mentioned if there is only one. Only one is mentioned in the text but there might be more. It's difficult because the text says there is only one high school, so this confused the system.