After a musical opening with Paul and his friends, Christina leads students in an upbeat song about how the earth is covered in water, but most of it is salt water so people cannot use it to drink and stay healthy. Next, two students, Ambria and Mariana, learn that while ocean water and fresh water may look the same, they can do an experiment to actually see the salt in saltwater. With guidance from their teacher, they set up a pie plate with some salt water and observe it over several days. As the water evaporates, they can see the salt left behind. They record their observations in a chart. Lastly, Paige and Elijah, explore one of the differences between saltwater and fresh water: density. Under the direction of their teacher, they first predict if various objects will sink or float, then they test their prediction by placing the object in beakers filled with saltwater and fresh water. They observe if the object sinks or floats and record their findings in a chart.