Uh, had to Nadin "critical thinking" to see what the flavor of the month is in educational theory.
"Critical thinking is the intellectually disciplined process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication, as a guide to belief and action. In its exemplary form, it is based on universal intellectual values that transcend subject matter divisions: clarity, accuracy, precision, consistency, relevance, sound evidence, good reasons, depth, breadth, and fairness"
So in short -- executive functioning skills (which allows you to become a critical thinker) is something you are born with. Some people are quite delayed in this area which can affect every aspect of their life. While they may be delayed, they can certainly be taught tools to help them overcome their deficits.
That all said, the bigger question actually is how many public school teachers are critical thinkers?
Answer: not many