App Inventor is a UI based tool to create mobile apps for the Android phone. It is a good tool for product managers and product designers to build functioning mobile app prototypes.
I have posted the code below. As you can see, the logic of this app is easy to follow and is clear to people who do not program for a living. Give it a try. It is a lot of fun.
Using similar logic you can write a "Roll The Dice" app. A great way to teach probability to kids. I wish I had apps like these when I was learning probability and statistics in school. Would have been a lot more interesting.