Have them sort change, and eventually to count it. It teaches them to gather things that are alike, it's an introduction to money and it occupies them for 15 minutes! Just make sure they're old enough to be past the point of putting coins in their mouth.
Have a yearly “review” right before school year. Raise allowance as appropriate. If they want more money, they’ll have to take on more responsibilities.
Take the family on periodic “spending fasts.”
As an exercise, go a day, a weekend or a week without spending any money. Make due with what you have.
Encourage participation. Tie in spending fasts with holidays, lent or in support of a cause.
Start saving money early. Save as much as you can.
There are plenty of things worth spending your money on, but be mindful about your money - Don’t p*ss it away.