Dunno what made me think of this just now. When I worked for IT in a school district way back in the 90s, a librarian told me she kept a supply of mouse balls in her desk because kids would steal them out of the school computers. What I remember about those balls was they picked up dust and crud off surfaces. Pretty soon optical mice came along and they were history.
I remember the teacher calling out “I cant see your screen” constantly and for unfair reasons, on chromeOS you can (frequently on accedent) abuse the security systems made to limit the damage of rouge extensions. Mainly the “no screen sharing on chrome:// and file:// tabs pages”. I also found a glitch that got patched to run the browser part on a higher privlaged UID (possably root? somthing related to OOBE? the lock screen itself? IDK). It was unstable, dangerous for the OS itself and could go to any site you wanted, this account had a blank chrome://policy and no extensions so anything was fair game. That got patched fast tho. My small group of friends still got to keep their chrome://flags changes even after the patch.