Disclosed is a computer-implemented method and system for tagging content for social interchange. When a user-generated post is received from a user device accessing a document from an online education platform for posting to an external social network, the system tags the user-generated post with a unique document-part identifier (ID) identifying a part of the document with which the post is associated. The document-part ID identifies the same part in both electronic and paper versions of the document. The post tagged by the document-part ID is posted to a live feed associated with the document-part ID on the external social network. User-generated posts from the live feed associated with the document-part ID on the external social network can be retrieved and displayed to the user.