Our app, Cradle, was inspired by the following metaphor: If the cradle stops rocking, the baby cries. The idea is that if the app's user stops answering the app's check-in pings, a pre-selected group of friends attending the same event will be alerted that you're possibly in danger. Our primary goal is to make it simple to keep people safe on campus. We wanted to create an intuitive app offering a proactive--versus passive--way to alert trusted friends that you may be in danger. The app works through negatively-triggered events based on existing Facebook APIs.