Normally, in the process of connecting to Google Classroom while making an assignment, Google will step in and ask you which account (or "profile") to use. You click the profile, and, if needed, specify the permissions (please give us all that we ask for!)

If, however, you immediately land on the TeacherMade Sign In page, it may mean that the Google account is already connected to another TeacherMade account. We don't allow more than one TeacherMade account to point to the same Google Classroom account. 

In that case, please contact us at support@teachermade.com, and let us know. We can find the account and disconnect it if needed.