How I Use It
Many students come to my school as intermediate students (grade 4 to 6) with a very little English language skills. We have one computer with Rosetta stone, but there's little else my ELL students can do when other groups are doing research, etc. I created student accounts and gave the information to all teachers the students interacted with. That way, they can record practice whenever they need. They can even see the progress of other ELLs with Duolingo accounts, too!
The set-up did take quite a lot of time. And, on my teacher admin side, it's entirely in Spanish! So, I utilize a lot of Google Translate and copy/paste to understand the site when I'm navigating Spanish-language descriptors. The tool is completely drill and practice, which only goes so far. But, it is a useful tool when other means for learning are not available.