If Classlink is not accessible you may use the Classlink Status Page to see if there is problem with the service.
Chromebook and ClassLink Access K-12 Parent Letter
Yorktown ClassLink Quick Start Guide
NOTE: If you are using a device that is not district managed you may need to install the ClassLink OneClick Extension if it is not available after signing into the Chrome Web Browser.
ClassLink is a single sign-on tool for education. This app allows students to access all sites and apps needed without the need to sign-in multiple times.
To access this app select the Classlink app.
Sign-in by using the Google Sign-in or QuickCard option.
Additional instructions on how to login into Classlink: Logging Into ClassLink