Update mobile-development.md

mobile-development/mobile-development.md

@@ -57,13 +57,13 @@ Read through the [Mobile Development slides](https://docs.google.com/presentatio
 
 Work through this React Native tutorial:
 
-- [React Native Tutorial: Building Android Apps with JavaScript](https://www.raywenderlich.com/247-react-native-tutorial-building-android-apps-with-javascript)
+- [Build a TODO App Using Expo](https://www.pusher.com/tutorials/build-to-do-app-react-native-expo)
 
 
 ### Independent Practice / Challenge
 
 - Spend the rest of your topic time (out of 4 hours total) converting one of your existing interactive projects into a React Native App. Be sure to start a new project/github repo.
-- If you finish, follow this doc on [running your app on a mobile device](https://facebook.github.io/react-native/docs/running-on-device).
+- You should use [Expo](https://expo.io/learn) for your stack.
 
 ### Supplemental Materials