They were quonset huts. My parents told me that when they finally tore them down, the neighborhood was infested with mice. I have pictures, although very vague, in the distance of before the school was built, but I don't see the huts.
Hancock was originally a K-5 feeder school for Stevenson which is located at 80th and Kostner. Back in the '90s, the school re-opened as Hancock HS, which pretty much was the overflow from Gage Park. After a few years and numerous problems and petitions by the neighborhood, Hancock finally closed and moved to the building that used to be Lourdes HS. Hancock (the building) is now a branch of Stevenson school and houses 7th and 8th graders. There is a new sign at the corner of 79th and Kostner with the name of Stevenson School.