Maria and Jane set up a lemonade stand one summer to earn money for a trip to the beach. They noticed that the hotter the day, the more glasses of lemonade they sold. They mixed up the lemonade exactly the same way every day: the same amount of sugar, lemon juice, and water. They added ice to the glass when they poured the drink. They always used the same size glass. They decided to chart their sales in order to figure out how much lemonade to make each day, using the weather forecast as their guide. Identify the independent, dependent, and controlled variables in the girls' experimental data.