You can join a class on Google Classroom
with a class link or code.
Go to Classroom.google.com.
Click the plus sign in the upper right corner.
Now click "Join class"
and enter the code you received for the class session.
Click "Join."
If you received an email invitation to a class,
click the "Join" option in the email.
You should also see an option to attend
when you sign in to your Google Classroom account
and click on the card that has your class in it.