You prepare three jars of salt water and keep each at a different temperature — one at room temperature, one heated with an aquarium heater to 80 degrees Fahrenheit, and one placed in a refrigerator. After five days you use a hydrometer to measure ocean salinity and see how temperature shifts the amount of salt mixed into the water.

Ocean temperature is how warm or cold seawater is, which changes how much salt the water can hold. In this project, you fill three jars with water, dissolve enough salt to match ocean salinity, and keep each jar at a different temperature. After five days, you measure the salinity of each jar with a hydrometer to see how temperature shifts salt levels.