Now is the time to educate tomorrow's citizens to care for the planet, and here is a lesson to help facilitate the process. Collect some marine debris and bring it into class. Have your class separate it into types and then test each item for buoyancy. Discuss the problems associated with floating trash. This visual experiment will make a lasting impression on your youngsters. You could follow it up with a long-term experiment on the decomposition rate of each type of trash.