If you have used App Inventor, using this will be straight forward.
In the mean time, here's a preview.
This is an App written with App Inventor. The source code for this is in the source directory and can be uploaded as a project to App Inventor if you want to reuse it. See http://appinventor.mit.edu/explore/get-started.html for instructions.
To install, later you can use either an android phone or tablet. Please see http://appinventor.mit.edu/explore/ai2/share.html for instructions and install application ( App ) in binary directory.
From Coder Dojo Castleknock team
Get the App here! ( APK file ) (open on your android phone) - will be available after match !
Get the Source code here ( Download and upload project to App Inventor ).