Grasshopper is a free app that teaches you to Javascript coding through a series of easy-to-follow tutorials. The free app, available for iOS and Android, starts off with an introduction to the basic vocabulary of coding before moving into the coding lessons. You have to pass the vocabulary quiz before your can jump into the lessons. Each lesson has a tutorial, a practice activity, and a quiz. You have to successfully complete each lesson before progressing to the next one. If you need to stop a lesson, Grasshopper saves your place until you can resume. Grasshopper offers an optional reminder service that will encourage you to practice on a daily schedule.

Applications for Education
I tried the Grasshopper app this afternoon and found it intuitive and easy to use. I can see middle school and high school students following the tutorials with little or no intervention from their teachers. The instant feedback in each lesson makes it possible for students to quickly see their mistakes and try again.