Duolingo: Language Learning in Interaction Design

I have been brushing up on my Spanish recently and a friend recommend that I try Duolingo. It has turned out to be a really pleasant (and effective) learning experience. The design of the site is excellent, and varied enough to be challenging and yet repetitious enough to promote memorization. I've noticed that the site has several commonly used frameworks for learning.

Connect an image with a term:   

Verbal repetition:

Verbal translation:

Spanish to English written translation:

Type what you hear:

hear.png

Each of these designs is extremely effective, simple, and intuitive. I did very little to "learn" how to use this tool. I just started using it and was practicing Spanish quickly and effectively right from the start. There are several key interactions that make this design work so well:

1) The response is always consistent: if you are correct or if you get the answer wrong it appears on the lower left and gives you the correct answer if you missed it. The question also repeats later in the lesson if you missed it.  

2) The use of sound (which I can't display here) is effective. There is a bell that marks a correct answer as well as when you hit "enter" to move to the next prompt. This makes navigation easier because sound is faster than sight. 

3) The top blue line tracks movement though a lesson. Each lesson is divided into 6-10 individual sections, depending on how many topics are included, and this makes it easy to see how far you have gone within each individual lesson. There are concluding marks are the end of each section.

4) Hovering over the Spanish words provides an English translation. This is helpful because the translation is hidden unless you need it. You can try to guess it beforehand, but hover over the word if you need assistance. 

5) The activities are varied. It moves from a verbal task to a written task to a visual task to a verbal task, and so forth. Varied enough that you don't get bored, and repetition is built into the program in less obvious ways because you might verbally respond to a prompt that comes up later in a written version. So by the time you finish the lesson, you have written and spoken the response. 

The overall organization of the site is quite good as well. For example, see above. This illustrates how the lessons are grouped together. In this case, there are 8 lessons about "objects" and each lesson takes about 3-5 minutes, so overall, this would be a 30-40 minute lesson.  As you finish each section, the conclusion screen tells you what you did, for example, what areas of language you have strengthened. 

And finally, the site keeps track of your overall learning by calculating your total proficiency based on which lessons you have completed. I'm not sure how accurate this 19% is in my case, but based on what they assume I have learned, it might be in the ballpark.  

There are a lot of subtle interactions that happen in Duolingo, and I would be very curious to know more about their design research practices. How did they come up with these particular lesson plans? What informed the process in terms of the amount of back and forth between verbal and written work?  On a purely aesthetic view, the site is beautifully designed, clean, and optimistically colored. I would also like to know if there are differences in the design in terms of the languages that are offered. So far, I have only worked with Spanish, but I look forward to trying out some new languages. Overall, I have been extremely impressed with this tool, which may be partly due to the fact that so many language learning tools are so poorly designed. It's nice to see a site that gets everything so right.