Suggestion for proper use of Duolingo as a teaching aid
Duolingo is ideal for the motivated student who mainly wants to learn a language, and for whom gaming rewards are a fun motivation and not an end per se. We all know that Duolingo is a fantastic tool for helping to learn a foreign language, but it's a tool that must be used wisely. That means recognizing what Duolingo is useful for and what it is not useful for.
I would suggest to teachers using Duolingo for their classes that they NOT make Duolingo accomplishments a significant part of grading. "Cheating" is far too easy on Duolingo for points or Lingots or levels to have any reproducible meaning. This is not meant as a criticism of Duolingo; it is an observation of how things are, based on the structure of the Duolingo site and the type of learner who most benefits from it.
I think it would make sense to award time spent on Duolingo, and perhaps for reviews done. It might make sense to have the students work through such-and-such lesson by the end of this week, put in five minutes or thirty minutes or an hour every day, and so forth. Something that encourages the students to take advantage of the great benefits Duolingo offers. But if you sweeten the pot too much by awarding significant grade benefits for Duolingo accomplishment, cheating will inevitably follow and the benefit mostly lost. Worse, those honest students who are motivated to learn will quickly become cynical when they see that the liars and cheats are getting the better grades.
You definitely make some good points. I have around 100 students and assign Duolingo as a weekly homework. Depending on their level, students have to finish a certain skill by the end of the week. For my students with special needs I ask them to complete one new lesson a day while at school. I have probably 5 or less who "cheat" that I am aware of. My much greater problem is students who fall behind and just give up. Particularly in the German, some students got stuck on the lessons using Dative and Negatives (both major grammatical concepts). I've tried to work 1-on-1 with those students and I've turned a few around. Some of them just don't care about grades and are harder to reach.
Getting points by constantly redoing old, easy lessons instead of by progressing through the lessons is often not according to the teacher's desires or even instructions. Answers can be Googled in other windows or tabs. Many quiz answers are available online.
One way to "cheat-proof" Duolingo is by removing all incentive to get points or credit by doing these things. In other words, make "cheating" worthless. That is my suggestion.
My problem is too many of my middle school students get bored with duolingo after about 2 months. They find online translations and use those to cheat. I can tell who is cheating because I give them biweekly written tests and find many of them fail. Seriously, duolingo is an excellent resource for teaching but it is essential to teach them outside of using duolingo. I teach at a title I school and most of my students are not willing to learn anything and with the exception of a few, will resort to cheating when possible. I will continue to use duolingo as a teaching tool because it beats using textbooks which always loses them:( and our state department of education endorses it!!!:)