All browsers will ask you for your permission before giving access to the mic and webcam.  On Safari this is that permissions dialog. 

Should the student click on "Never for this Website" they won't see the dialog again on that site. 

To go back they will need to visit the "Safari -> Settings for this website" page. But its a good idea for all your students to visit this page and tell Safari to permanently remember the "Allow" selection.


Visit the "Safari -> Settings for this website" page.


Then toggle BOTH the microphone and camera settings to "Allow"