Learn English with Babbel.com is an app that lets you learn multiple languages, including English.
Functions:
It offers English classes that involve reading, audio pronunciation and spelling and basic and advanced vocabulary; lets you contact native community members to practice English (chat, messaging) and access offline classes.
Activities:
You do grammar exercises, practice word pronunciation and extend your vocabulary according to your level.
How to use:
You need to choose the language you want to study and register using the user name and email, then simply confirm the subscription via email and start the classes.