What is the 'reverse tree' people speak of?
Just the tree done backwards or what?
I had a question about this too... why is doing the reverse tree thought to be helpful? Is there really much difference in the material to be gained doing the reverse tree?
1) It's a review of older material.
2) There are occasionally different words used, or at least earlier in the tree. I'm about 2/3rds of the way through the Spanish for English tree and haven't hit diseñar (to design) yet there; but have come across it on English for Spanish tree in the first 1/6th of the tree.
3) They expect you to be able to actually speak Spanish there. Because it's aimed at people who already know things such as that direct object pronouns go in front of the verb and how reflexive verbs work, it forces you to use what you've learned on the forward tree.
4) You can feel better about your frustrations and silly questions when reading the comments. All my complaints about "Why do you use to take to mean to wear?" are matched by Spanish speakers asking if the verb in "El hombre usa zapatos." translates as "uses", why do they have to use "wears" instead.
I haven't done it, but I think it reinforces the words you have already learned and you get to keep using/playing duolingo.
Personally, once I finish the tree, I will look into other resources and the "immersion" features.
Because the site thinks you are a spanish speaker and presents everything in spanish, and exposes you to the more difficult spanish topics sooner. I am almost done with my reverse tree.