For German I used to try the exercises on my commute, but suddenly the app expected me to use "dem" instead of "der" without any explanation. I can't be the only one with this problem, right? Or is there a "new concepts" tab that I've never seen?
I probably have a different perspective than most, but here's why I enjoy Duolingo's style:
The first foreign language I began learning was Spanish. I took it throughout high school and college. I was taught theory first, so I could understand most of what I'd read or hear following the new lesson. Running the input through the theory I'd established in my brain worked, but it was very slow and took a lot of practice to speed up my speaking and understanding.
When I was visiting my wife in Brazil while we were dating, I learned Portuguese very differently. Although they were aware that I didn't speak Portuguese, many of her friends and relatives did not let that reason hold them back from speaking it to me anyway. So I was bombarded with the language, and slowly began to understand more and more. First, I'd only understand one word in a phrase, then 25% of it, then 50% and so on until I reached a critical point where I understood enough of what was being said that I could use the context of what I did understand to infer the rest and learn that too.
Learning Portuguese was so much quicker for me. I still know more Spanish theory, but I still speak and understand it too slowly to consider myself fluent. On the other hand, Brazilians tell me all the time that they're impressed with how well I speak Portuguese.
I think the jumping right into the deep end style of learning Duolingo offers is fun, but may not be the best for everyone.
http://www.amazon.com/English-Grammar-Students-German-Learni...
http://www.amazon.com/Hammers-German-Grammar-Usage-Edition/d...
But they definitively go well together. You see a few examples of case usage, then you read the theory, then after you use it again, it magically "clicks" (for me at least), and things make a lot more sense.
The 'explicit' reinforcement /'implicit' learning couple is a great way to learn I think -- you grasp it intuitively and yet if you are faced with a new or tricky example where your experience will fail you'll be able to make a principled choice by explicit reasoning ("Oh the case here is * such and such * because of * this * therefore the pronoun here must be * that one *").
It took me ten years to be as proficient as a ten years old kid in my first language. So I don't think the way we learn our first language is necessary the best way to learn language in general.
And, I would say I was passably proficient by about 7. At least enough to read relatively simple non-picture books.
1) You have the ability to translate. You already know the concepts and ideas - you don't have to abstract meaning from noises - you already know the meaning, you just have to correlate it
2) You understand grammar concepts. It may be quite different in your target language - I have been learning 日本語 for some time, and grammar is wildly different from English - but there's still a lot of things you only need to learn a few differences of, vs. having to learn the concepts from scratch
With our first language, we have to sit there and learn by what sounds right vs. what sounds wrong. This is so hilariously trial and error and completely inefficient that it makes the entire process far slower than it would be if we had any other way to do it.
How long does it take you to figure out verb conjugation the way you learn a first language? Quite some time. You probably don't get it fully right in all cases until you later enter classes that go over the grammar rules. In Japanese, I was conjugating verbs, including irregular and negative forms, at multiple politeness levels, in about two hours of learning conjugation. And I rarely made mistakes after that. Why? Because I already understand verb conjugation. It's a concept I have a solid grasp on in my native tongue, and only needed to learn a few new rules to graft onto the existing framework.
Duolingo is almost exclusively focused on translation, which is absolutely not how most of us learned our first languages.
(Also, in case you haven't yet worked it out or looked it up somewhere else: you need to use "dem" with masculine and neuter indirect objects, often translatable into English using "to" or "for", and with certain prepositions. It is the dative masculine/neuter definite article.)
Duolingo has a full-featured web version: https://www.duolingo.com
I find it vastly easier to use than the mobile version for that reason.
As for what you're asking, I guess it's really hard for english-speakers. I'm bilingual, and coming from spanish and being fluid in english, it's a lot easier. The main thing is: nouns have a gender, and the article ("the") do as well. Do "die" is feminine, "das" neutral, and "der" masculine.
Verbs also conjugate differently according to gender.
That said, especially for German I would've liked more theory too. And some people just seem to have a preference for learning in a more formal/theoretical way.
I have a non-fluent understanding of what "subjunctive perfect" means in my home language, but I guess I deal with it OK.
As such, I don't find it valuable when I see that section on Duolingo and think "OK, it's subjunctive perfect time!"
Of course, we do study grammar in our own language. We do it at school.
For the first German lesson, these are on capitalising nouns, grammatical gender, umlauts and verb conjugation.
I wish they'd add it to the app!