"When a child asks you something, answer him, for goodness’ sake. But don’t make a production of it. Children are children, but they can spot an evasion quicker than adults, and evasion simply muddles ’em."
-Atticus Finch, To Kill a Mockingbird
Kids are remarkably perceptive creatures. Even infants pick up on parental cues and follow our lead, regardless of the emotion we emit. If you have something major going on with your career, marriage, finances, health you name it your children are picking up on it.
Your best course of action is honesty. Pretending like nothing is wrong does nothing but send mixed signals to your kids. It makes them question their own instincts and judgments one of the cruelest things you can do to them. When your child approaches you with a tough question especially one involving a perception they have be simple, be direct, and be honest. You’ll actually be doing them a tremendous favor.