There is a folder on Snapchat you may have never heard of, but chances are your teen has heard of it and is possibly using it.
The folder is called "For My Eyes Only." It is hidden deep inside the app, and the folder is password protected. The folder does have to be enabled in Snapchat's settings.
To see if your teen has this folder enabled, go to Snapchat and select the icon below the camera button. Then swipe all the way right. If the folder is enabled you will see it there.