Preface

We think writing computer programs is fun and that those who can do it can make a difference to the world around them—sometimes in an almost magical way. But when you start out, it’s often hard to see how the programs you write can make any difference to anyone—for example, you might just be drawing simple shapes or adding up a bunch of numbers.

Back in 2012, we started using App Inventor with teachers and children and discovered it was a brilliant way to make computer programs that worked in the real world. Beginners could perform useful, imaginative, and fun tasks like a GPS treasure hunt or a homework excuse generator. The App Inventor books that helped us learn were great, but we wanted to focus on helping school-age kids and beginners become app creators. Paula proposed that we write a book, and within a day we had the original contents page and app list. This initial speed lulled Paula into a false sense of security, and colleagues now remind her that she waved her arms around and said “It’ll only take us 12 weeks!” She was only off by a factor of 8 ...