I'm just thinking, what if you do it the other way around: allow the
camera by default, but block it in the teacher app and enable when
needed?And did you try to restart it, after "switching on" the cam?
how can I undo the command ln -fs /Library/Desktop
/System/Library/CoreServices/DefaultDesktop.jpg in macOS High Sierra and
El Capitan? just updated the devices possible to an higher OS and
trashed those not update-able!