I highly recommend these two language apps as well.
Vocabulary Apps:
Duolingo – This is a great app for learning vocabulary and for practicing sentences. You can “level up” in the target language and compete against your classmates for the most points. The class link is here: https://www.duolingo.com/o/yzazhk
Memrise – There are many English courses available for students. Memrise has students associate words or images with vocabulary to help students remember vocabulary. http://www.memrise.com/courses/english/english/?q=intermediate
So, You Think You Can Teach ESL? 