Students and other teachers can join your groups in two ways: by using the Group Code or the Join Group URL. To determine which group-join method that is best for you and your students, it is important to understand the differences between the two.
The group code is a private piece of information that, when unlocked, gives immediate membership to your group to anyone who uses it (like giving them the key to a locked door). Because anybody who uses an unlocked group code is added in to your group right away, the group code should only be given out privately to individuals you want to join your group. For example, passing it out to students in class, emailing it to students, or writing it on the white board for your students (and erasing it afterwards) are secure ways to pass out the group code, but you would not want to post them on Twitter or your public web page.
Group codes will lock automatically after two weeks to ensure that the group owner maintains control over who can use the group code to join their group. After a group code has been locked, it can still be used to join your group. However, when a student uses a locked code, they will be placed in an approval queue for the group, and the group owner will receive a notification about a group join request, and has the option to approve or deny the join requests. If you would like students to be able to join your group without your approval after the code has been locked, you can easily unlock and reset the group code at any time, generating a new group code that students can use to join your group.
The join group URL is a more open way of inviting people to join your group, and requires the group owner to approve membership requests (like they are knocking on the door of your classroom). The join URL can be shared publicly, for example to invite members to your group via your website, blog, or Twitter account. When students or teachers enter the join URL in their browsers, a group-join request will automatically be sent to the group owner to approve or deny. Thus, the group owner always has control over who enters a group via the join URL, which is why they can be shared publicly.
If a student is not logged in, or has not yet created an account, when they use the join URL, they will be prompted to do so after entering it into their browser. After logging in or signing up, their join-request will be submitted to the group owner for approval.
Both group codes and join URLs can be used to join groups and create accounts.
Both can be found by the group owner on the left panel of the group's page.
Group codes should NOT be shared publicly. Join URLs can be shared publicly.
Group codes, when unlocked, allow users to join a group without being approved by the teacher. Using a join URL always requires the group owner to approve the group-join request.
Group codes can be reset to generate a new group code. Join URLs always stay the same.