A worksheet can be classified as either published or unpublished at anytime. This will determine what worksheets are active that can be then allocated against a task or created on an ad-hoc basis. 

When adding a new Worksheet simply toggle on or off the 'published' toggleIf you need to publish or unpublish an existing article press from the list view. Or from the detailed view then . Toggle the 'Published' button to alter. 

In the worksheet list view  will appear next to all of the worksheets that are not published.