To add a Google Scholar Content link to your classroom go to a content area and select Google Scholar Content from the drop-down menu located to the right on the gray tool bar, click go.
On the Add Google Scholar Content screen there are clear instructions on how to add an article and citation to your classroom. After you submit and create the Google Scholar Content item you cannot successfully modify the item.
The modify button will create another item instead of modifying the existing item. Your options are to remove the initial item after using the modify button or, remove and redo from the select Google Scholar Content.