How to prevent confidential documents from appearing on Google Drive

If you are running into the issue of Google Drive showcasing confidential documents in front of class, here are a few suggestions that can help you hide them from view:

If you are using slideshows, open the Slides app instead of your Drive. This will only display Google Slides and prevent private Docs from being displayed.
On your laptop, in Google Drive, open settings. Scroll down and look for Suggested Files. Uncheck the first three boxes. This will arrange your drive in folders first, and eliminate the priorities list. This will only take effect on your laptop, not the Drive app on your Promethean.

On your laptop, open Drive and find the document. Right click on it and choose "not a helpful suggestion". To do the same on the Promethean, click the three dots next to the document, scroll down and choose "not a helpful suggestion." This will remove it from priorities list and should prevent it from reappearing.
Add some empty text lines to the top of your document so that the body of the document are not visible even if it shows up as a thumbnail.