How I Use It
I use this product with my ELL classes and students. The students are able to put the Duolingo website in their native language and they are able to do lessons at their own pace. Students, if they are more advanced, are able to test out of sections to unlock the deeper and more difficult language sections. This allows for very personalized vocabulary and grammar building skills within one class.
Duolingo is not a stand-alone lesson replacement, however. I do a little pre-teaching before we delve in to give the students a better understanding of what they are learning and why. This helps the Duolingo lessons "stick" better and gives them a better start on the lessons. But, in all, Duolingo is a great vocabulary builder for any language and works well in the classroom as homework or further practice.
I think this website is great for students learning a new language. As a tool, it's intuitive and easy to use, which is important for students learning a language. Anything intimidating can be off putting, and so far I have students enjoying this and learning from it. It really allows my lessons to be better supplemented with extra practice that is at the student's own pace. However, I think that if you are expecting a tool to use on its own, its good, but limited. But, if you supplement it with your lessons it's a very powerful tool.