In grade school, I can think of two specific examples where we were taught a lesson that was supposed to develop critical thinking skills. The infamous Tongue Map and the Mpemba Effect (hot water freezes faster than cold water)

Both of these are examples where an authority will confidently tell you a fact (which is bogus), then have you conduct an experiment which ought to disprove them.

I did the tongue map in kindergarten. It's obvious that it doesn't hold up, but when I told my teacher about it she said I must have been doing it wrong. Later in grade school I did the experiment to 'confirm' the Mpemba effect. Despite the evidence before me I still lied on report and said that the hot water froze faster because I thought that's what the teacher wanted. Apparently so did half the class, and because we did the experiment we all got a passing grade and were never told that it was supposed to be false.

So I dunno. I guess they ought to teach critical thinking at a young age, but the instructors have to buy into it to.