Strengthening doesn't work
Hi, when I click on the "strengthen skills" button and finish the revision, nothing actually gets strengthened! And when I do the strengthening one by one (I go into each lesson that needs strengthening and click on stengthen), it only fills the bar with the first lesson I do, then for the rest, nothing happens! So now, I have about 15 things that need strengthening and can't do it... Does this happen to anyobody else? Or am I doing something wrong? Thank you for your advice
There is general agreement that using the "Strengthen Skills" button is mostly ineffective and that you have to strengthen each skill set individually. I'm not sure what the second thing you're asking about it, but doubt I could help you with it, anyway. Maybe someone else knows?
When you have a lot of skills that need strengthening, you're not going to get enough exposure to any single skill to have the algorithm count it as "strengthened."
Think of strengthening skills like finishing a big holiday meal, like Thanksgiving in the States: you have the potatoes, the sweet potatoes, the green beans, the turkey--a lot! You're never going to finish it, right? Especially not if you only get 20 small bites! If those 20 small bites are spread out across all the foods, you're really never going to finish it. That's what the general strengthening button does: it gives you little bites of everything that's on your plate. If you don't have a big diversity of food on your plate, if you just have the mashed potatoes and the turkey, then you'll probably finish your plate, though maybe you still need more than 20 bites. But if you have a lot, then it's going to take you seemingly forever. It's made even worse if you actually start filling up on stuff that's not part of the holiday meal (skills that don't need strengthening), like the algorithm seems to be doing.
On the other hand, if you focus on one dish (like strengthening a single skill), you'll be able to finish all your sweet potatoes in 20 bites. Maybe it takes longer because you actually have more to strengthen/eat than the icon says you do. Maybe it takes longer because you keep hovering over words or getting the answers wrong. But skill-by-skill should be more efficient than general strengthening.
At least, that's the way it should work. If you haven't read this, it might be interesting: http://gregreflects.blogspot.com/2014/12/how-to-make-gold-duolingo-tree.html