Subtitles section Play video Print subtitles This Great Big Story was made possible by Wells Fargo. Established 1852. Re-Established 2018. (upbeat music) - Science can make a big difference, anywhere from just a simple reaction to a big experiment. If you just find the right application, science can save the world. My name is Gitanjali Rao, and I'm 12 years old. I'm a scientist. I invented a device called Tethys that detects leads in water faster than any other current techniques out there today. I was appalled by the number of people affected by lead in water during the Flint water crisis. I wanted to do something to change this for the residents of Flint and places like Flint all over the world. My device includes a core device and a disposable cartridge with the carbon in a tube sensor. You dip this disposable cartridge into the water you wanna test. You pull out your phone, open up the Tethis application, and connect over Bluetooth to get the results of safe, slightly contaminated, or critical of lead levels in your water. My advice to other kids who wanna save the world is do not be afraid to try. I failed like four or five times, but I got back into the lab, did it again, and then it was like the a-ha moment when everything kind of started coming together and, you know, the device is born. I think that science allows me to look at different approaches to solve real-world problems out there today. It's important to take other people's problems and make something to help them with it, mainly because we're all one big community, and it's our duty to help other people.