Hannah Bloch

Three years ago, we published a story about a small start-up in Kigali, Rwanda's capital, that was seeking to make homes more sanitary by replacing dirt floors with sealed earthen floors, which are up to 80 percent cheaper than concrete.

Nawaz Sharif, who served until Friday as the 18th prime minister of Pakistan, is no stranger to his country's courts. In three tumultuous go-rounds as premier over the past 27 years, he's been embroiled repeatedly in judicial cases on charges ranging from corruption and contempt to terrorism and treason.

On an overcast late-spring afternoon, a group of bird lovers from the Earth Conservation Corps are in a boat on Washington, D.C.'s Anacostia River, and point out an osprey circling overhead. "This is like their summer vacation spot and where they have their young," says Bob Nixon, in the boat. "Then they spend most of their lives in the Amazon."