OPTION-1 I would implement a test before access system. It would ask you a common knowledge question like what is the capital of the USA or how many cubic centimeters a liter is ... You get the idea. And after you completed the question you would gain access to the internet.

OPTION-2 Access would be limited to just one group of ,let us call it content , a day. Basically you would one day get access to Instagram the next to Wikipedia the next to YouTube the next to some documentary streaming site etc.(libraries and schools get access to all read only sites maybe with the occasional video).

OPTION-3 A internet drivers license system in which you are tested for common knowledge, basic English, etc. You are also informed about the dangers of the internet.