We use a variety of tools to track the balloon while in flight and once it is on the ground. They usually burst between 85,000-100,000 feet and we are able to "talk" the balloon's payload while in flight using radio technology. Once on the ground, we deploy a device via cell phone that has been sleeping in the payload and it calls us and relays its physical location to use via Google Maps. We can then drive to it and locate it. It is a great after school STEM class and the kids who sign up love it. They do all the design and research for the payloads and then learn about all the technology on board so they can run and operate it all. We like to use iPads and iPhones when we track and while we are talking to the balloon's payload.