study hall 
noun [mass noun] North American
1The period of time in a school curriculum set aside for the preparation of schoolwork: we were together only in study hall and at lunchtime...
- My day couldn't have been better until Sean came up to me during 6th period study hall, the last class of the day.
- During last period Veruca and Caleb were sitting in study hall talking.
- I just had to find a way of hiding it from my teachers to make them think I was studying in study hall.
1.1A schoolroom used for study.Then we follow him to a classroom, to the dining hall, the playroom, study hall, the chapel, his room and finally the infirmary, where Stephen goes after he wakes up sick one morning....
- So instead of sitting in study hall like I was supposed to, I took a hall pass and left in search of something to do.
- My only time to talk freely in school besides study hall.