Did you ever have a Lemonade Stand? This fun simple game simulates the process.
You determine how much to charge for a cup. Then decide how many lemons, how much sugar, and ice you will use.
Make sure to take into account how hot it is out. If it's hot and sunny, tons of people are going to want a cup; so stock up. If it's rainy and cold, you won't need as many supplies. Remember that at the end of everyday you have to throw out all of your left over supplies.