Question for multilinguals
For those of you mastering at least two languages... On top of doing the reverse tree, would you recommend doing triple trees? For example, being Spanish native and after conquering the spanish-german tree (and its reverse) would you recommend starting polish through the spanish-polish tree or through he german-polish tree? Even if more difficult, it could help learn polish and practice german at the same time. PD: still not there...
It is always a good idea to challenge yourself. However, when learning a new language, it's probably a better idea to stick with learning it from your native language first. Even after conquering both trees or another language, there are always going to be small nuances that you don't get, so if you learn it from your native language, there is a better chance of catching those. I'd say to do the Spanish-Polish course first, and then try doing a German-Polish or Polish-German course after that to increase your understanding of both. (Although they don't have the two yet)
It would be great to have Spanish-Polish or German-Polish tree, but unfortunately there are no such courses on Duolingo. Perhaps on some other websites.
Personally I am planning to try Russian-Spanish course one day, but I'm definitely not ready yet ;)
I do that. My German and Italian flags on my profile are from French, and my French flag is from German. I love doing that!
I've been doing those, as you have called them "triple trees" for quite some time, I think that if you have at least B1 level in both of the foreign languages, you'll be fine. Actually, there's even a name for learning a foreign language via another foreign one - it's called laddering and I find it a very smart approach to learning - it surely saves a lot of time and gives you an opportunity to use the foreign languages you know in practice.
In most cases, I wouldn't recommend it. But then there is this possibility that a language you want to learn is grammatically more similar to the one you've learnt before than to your native language., in which case it's easier to translate it to the former, therefore you're less likely to make a mistake.
That, or the language may just not be available as a course for your native language :)
I don't have a good answer for you, but as a native English speaker who is reasonably fluent in Spanish, some parts of Spanish have helped me with Polish pronunciation. The 5 Spanish vowels correlate more closely to Polish, and the Spanish diptongos (ia, ie, io, iu) seem to create a very similar effect to the soft Slavic consonants (palatized). But I still use the English to Polish Duolingo.
Now, studying Ukrainian, I find it surprisingly easy to learn Cyrillic alphabet. But my mind goes naturally to the Polish sounds and consonant clusters, which I have practiced, rather than English. E.g., Щ feels like szcz more than shch. Polish helps me learn Ukrainian, even within the English to Ukrainian Duolingo.
So, you will use all of your languages to learn a new one, even when learning in your native language. Some Polish sounds may seem easier if you correlate to German, Spanish will be better for others. Your German studies should make it easier to understand the grammatical concept of cases in Slavic languages. The Duolingo method facilitates this fluidity -- I see a picture of a house and think dom (Polish) and дім (Ukrainian). And casa, of course.
Dana (My Spanish is not from Duolingo, and I converse in Spanish frequently. But I have gained some new vocabulary and grammar corrections through Duolingo)