Period 1: https://classroom.google.com/u/0/c/Nzk5NzkzNzQ2MzU5
Period 2: https://classroom.google.com/u/0/c/Nzk1ODEwNDA3NjI2
Period 4: https://classroom.google.com/u/0/c/Nzc0NjkwNjAwMzQy
Period 6: https://classroom.google.com/u/0/c/Nzk1ODEwODM3NjEx