There is a set of three words in the English language which contain great power. These three simple words, when uttered honestly to one you care about, open whole new worlds of possibility. They are the key to self-growth, and of a deeper and more positive relationship with those around you.
These words are: I don't know.
If someone - and particularly a child - asks you a question about how something works or why something happens, and you don't know the answer or feel confident to explain it properly, the most important thing you can do is to admit, "I don't know". Once this has been said, the two of you can seek out the relevant knowledge and learn from it.
At some point in our lives, we must learn that people in positions of power or authority don't know everything, and that seeking out knowledge from a wide variety of sources is the best way to learn about the world. Teach your children that, and they will be better equipped to deal with the world they grow up into.
Once you are comfortable with "I don't know" as three of the most powerful and positive words you can use to your loved ones, add to those another powerful set of three words:
dmmaus, in the annotation to his webcomic Irregular Webcomic, had this wisdom today: