Every time a lecturer says, 'As we all know from high school...' and then proceeds to talk about something I've never heard of in my life, a part of me dies inside😭. Why do they expect us to know things they haven't taught? Am I the only one?

Every time a lecturer says, 'As we all know from high school...' and then proceeds to talk about something I've never heard of in my life, a part of me dies inside😭. Why do they expect us to know things they haven't taught? Am I the only one?