How I Use It
I have used and recommended Duolingo for a while now. It's an easy to use language learning app that allows for customization, practice and levelled learning. I have used it when teaching a Learning Class where students created their own learning goals and plans. I have used it when tutoring students in Spanish and French. I have also used it for personal language learning as I have worked on boosting my own Spanish and French learning this past year.
The app and website are ideal for individual learning, for homework to supplement language classes, particularly when students are studying a language that is not widely spoken where they live. You can do it for as little as 5-10 minutes per day which helps you keep the language fresh in your mind.
The use of badges and levels and lingots helps keep students motivated to practice every day to keep their learning streaks going. You can use your lingots to unlock different levels, which is also a motivator.
You could use Duolingo for homework activities, for the beginning of language classes while everyone is getting settled and/or for students who finish their work early.
Duolingo is more of a learning than a teaching tool but it is a good one. The only negative with it is that there is not enough opportunity to produce the target language and to study the language in a more focused way. If you could do these two things, I think the app would really help learners become more fluent rather than just being able to understand more.
This is a great learning tool but limited in terms of building true fluency.