This picture shows the Grand Ethiopian Renaissance Dam (GERD). This massive hydroelectric dam holds back water from the Blue Nile River to create electricity for millions of people in Ethiopia. 

How does stored water behind a dam get turned into electricity?

What is one benefit and one drawback of building a large hydroelectric dam, and who (or what) is affected by each?

Large hydroelectric dams can generate low-carbon energy for millions of people, but they can also change ecosystems and affect the livelihoods of people living nearby or downstream.

Name one environmental factor, one economic factor, and one social factor a country should consider when deciding whether to build a large hydroelectric dam.