I need to do sign ups for group activities during a course. I've gone to the People tab and created the appropriate groups that participants can sign up for. By sign up I mean they can choose which group they can join. I need to limit these sign ups in regards to time. What I mean is that I need to create a window of time that participants are able to sign up/join these groups, so a specific start and stop time. I've looked through Canvas and tried to look it up online but I haven't found any help so I thought I would try here.