I am always telling my children to think. When they hear something, no matter what it is, they should always question, "Does that make sense?" Even if it makes sense, it's not necessarily right.
DD12 just did a science experiment from Jay Wile's Exploring Creation with General Science. In the experiment she proves that heavier objects drop faster than lighter objects. She dropped a sheet of paper and a book. Of course, the book hit the ground first.
In the very next experiment, she found that the conculsion of the first experiment wasn't correct by dropping several other items from a flat sheet of paper, to a paper clip, to a rock, to a book to a crumpled up sheet of paper.
These two experiments are just one example of what I am talking about. There are so many issues in the world today that "prove" themselves to be true at face value. Many members of our society will accept a given "fact", not question further and just go with the crowd.
I want my children to grow up to be thinkers. They may not know everything there is to know (Who can know everything?), but thinkers have the ability to seek information about what they need to know.