Dear Ikumi, The term „critical thinking“ can be found in many different contexts. As your questions implies you are a student at a university and therefore I would try apply this term in an academic context: Critical thinking has to do with independent and some kind of reflective thinking to detect and solve problems, using logical and structured approaches. It deals with thinking ahead and having a look at the big picture. When applying critical thinking one might also apply critical reasoning (logical thinking, deductive approach). It has less to do with just collecting and “only” memorizing facts and data. Please let me know if this is too abstract and I would try to give you some examples. Please be aware of the fact, that this explanation is very simplified and mirrors only my opinion. Kind regards, Paul

I think your professor refered to "key thinking or important thinking".