Critical thinking is the most important part of education because it makes you question and evaluate an idea before accepting it. Stuffing things into your head does not work because it makes you a data storage rather than a bright person. What matters is not how much you learn, but how you learn it through critical thinking, and how you view things in the right contexts.
The process of critical thinking starts with a humble attitude to question your long-held beliefs and asking why things happen that way. It’s not a complicated process, your common sense and reasoning will guide you along the way. Any regular person has the capacity to do it unless being suppressed or brainwashed.
The flawed flat-earth theory that lasted for so long is an excellent example of the suppression of critical thinking. If you look over the horizon particularly over water, you can easily see the curvature of the earth. In addition, the sun and the moon are round objects moving along predictable paths in the sky. Why should the earth be different? How could people be so blind to these facts for thousands of years? I can think of two reasons: First, nobody dared to challenge religious doctrines about the earth-centered universe for fear of persecution. Second, ideas could only be transmitted by words of mouth due to the absence of modern communications technology and the fact that the majority of the population were illiterate.
In this modern age, although critical thinking can hardly be suppressed, it is clouded by political propaganda, commercial advertising, and bogus ideas posted on the Internet. As a result, learning the truth requires filtering out all the untruths, which does not seem to be easier than in ancient times.
If you really care about the truth, you must question the validity of the ideas you hear and see everyday. I can assure you a vast number of them can be discarded as garbage.