This Investigating Properties of Water: Temperature lesson plan also includes:
Investigate how temperature affects the density of water and stratification that occurs in bodies of water when temperatures vary. Water of differing temperatures is given different colors to see the layers that form. The lesson is meant to apply the knowledge gained from the experiment to real-life tide data, but the link is no longer valid. Also, the lab sheet is not included, so you will need to create your own. Otherwise, this is a fine activity for middle school science.