1) A group of people who sing songs together - a choir (хор)
2) To act in some play or to prepare the concert - to perform (исполнять/выступать)
3) Pupils have their lunch in this room - a canteen (столовая)
4) You can play tennis in it - a court (корт)
5) Pupils study Science in this room - a science lab (лаборантская)
6) You can find books, magazines and CDs there. - a library (библиотека)