How do I sign in to Classroom? – Computer – Google Help

Go to classroom.google.com and click Go to Classroom. Enter the email address for your Classroom account and click Next. Enter your password and click Next. If there is a welcome message, review it and click Accept. If you’re using an Google Workspace for Education account, click I’m A Student or I’m A Teacher.

https://support.google.com/edu/classroom/answer/6072460?co=GENIE.Platform%3DDesktop&hl=en