Ten-year-old Callie Hilton was only required to do a school project on solar energy. She was so enthused about what she discovered during her research that she built a small house for the homeless to take shelter in. Callie lives in the state of Georgia, in the United States. Her invention uses solar energy and is low cost: only 32 reais per shelter.

Initially, Callie collected recyclable material and a few old objects, such as a TV, to build a sustainable shelter. She used YouTube videos to help her build a mobile shelter that could fit a mattress, a drawer to keep clothes and storage containers for water and waste.

The house has a small rainwater collecting system, a food container that is heated using solar energy, and a solar panel that can power an indoor light-bulb.

The house, which the girl named Callie’s Coop, weighs just 11 kilos. To help people move it, she made a hand-pulled cart that moves it from one place to another easily.

Questions 

How did Callie come up with the idea of building a cheap homeless shelter?

Which materials did she mostly use?