One day Google Classroom will have an integrated Google Calendar feature. For now, we have to do a work around.
- Create a class calendar that is separate from your personal or work one.
- Click on the next to the new calendar that you have created.
- Go to Calendar Settings.
- Scroll down to Calendar address and click on the html to get the html address.
- Highlight the html and copy the address.
- Go to the About tab in Google Classroom and add Calendar to the page.
Images courtesy of Joe Guinane.