How Do You Know if You Don't Know Something?

For me, i take a course and i'm sat there hypocritical the entire time. The ship if you don't know it to start withb what metric are you saying in your head? I normally have done a little bit of research and understanding before i begin but i don't think i necessarily take a course to learn something. Most courses have unlike communities talking about the information on twitter, social media, in a group and a discord somewhere. So all the stuff youll get in a course, you can find on a line, if you know where to go and you have the time to find those places.