The system hides the "Join Us" button after you press it. So, if you don't see the button, it means you've already joined! You can also check your "myPage" to see the groups you've joined.
We want to know what you think of us! Not only do we appreciate it, but your feedback--directly--helps us improve our site and our content. We read every single response that we receive, and your feedback will be used to create a better learning environment.
Please do not hesitate to ask any questions.