Mary works at a fast-food restaurant. The customers' orders don't always add up to even amounts. Mary needs to learn how to make change.
She puts coins in front of her. She has a penny, a nickel, a dime, and a quarter. These are the coins that most people use. She knows that a penny is worth one cent. A nickel is worth five cents. A dime is worth ten cents; a quarter is worth twenty-five cents.
Next, she gets her bank and empties it. She separates the coins. She makes piles of pennies, nickels, dimes, and quarters. This is the same way they are separated in her register at the restaurant.