Cannot add a google spreadsheet in planner
Brian, Google spreadsheet files like this are just pointers to web documents: they don’t contain the information you are trying to share. You can see this by looking at the size of such files on your computer: they are all the same size (from memory 249B).
It might still work as a link though, but you need to add the file extension (.gsheet) to Gibbon’s list of allowable extensions. You can do this under Admin > School Admin under the main menu, and then Manage File Extensions in the module menu on the side.
Or, if that does not work, just insert the link to the file using the link button in the visual editor.
Good luck : )