Eat your crusts!  I was told it would put hair on my chest - a notion that did nothing to encourage my sister to eat her crusts.  I'm sure that my parents were much more concerned with having to throw out food than making sure I got the benefits of bread crusts.  Now we have proof that it is good for us - even if it doesn't put hair on our chests or make us taller.  It's good that someone questioned the old wisdom and put it to the test.  Some old wisdom isn't so wise.  Testing is important to prove what is good.

Think of other old sayings that have proven true and ones that haven't.