There's nothing quite like a glass of ice-cold, freshly squeezed lemonade. Lesson seven of this series explains how the water humans need to survive can come in many forms. Teach your class about how much water humans require every day before making glasses of lemonade and studying the water content of other common beverages. As an extension, bring in foods with high water content like watermelon and tomatoes to demonstrate how foods can also provide humans with water.