Conditions affecting the hearing bones: otosclerosis. Otosclerosis is the most common cause of hearing loss in young people. It's a condition of abnormal bone growth affecting the stapes, the third of the three little bones in the middle ear.
Hydroelectric dams use water to produce electricity. Natural water resources include lakes, rivers, streams, ice pack, groundwater, precipitation and oceans. As global climate change begins to affect the distribution of water resources in the United States, water use in all sectors is coming under increasing scrutiny.
1 Brainstorm with your students about how people use water. We need to drink water in order to survive. We also use water in many other ways, such as bathing, swimming, watering the lawn, doing the laundry, etc.  Ask your students where we get the water we need. Have them brainstorm natural sources of water.