If you are using Google Classroom as your LMS, you should not create a duplicate class directly on CK-12. Students should only access assignments made to Google Classroom through Google Classroom. Google will pass to us the credentials the student uses to log into GC, and we will create an account for them if needed, or log them into our system on the back end.
Click here to learn how to create assignments of CK-12 materials to your Google Classroom:
Click here to learn how to access reports for CK-12 assignments through your Google Classroom reports.