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Practice no longer selecting weakest words

I've noticed today that for both the website and the Android app (and presumably for the iOS app), the practice options (i.e. "Strengthen Skills", "Practice Weakest Words", "Lesson Practice") no longer select words with the lowest strength for improvement as they have in the past. Previously, using these options would pick the ~9 weakest words from your vocabulary, which could be seen by sorting the vocabulary list by strength, low to high. However, as of today, I've noticed that these options (which are really just the same option with inconsistent names) are choosing the oldest words in the "last practiced" column instead.

This change has rendered it impossible to actually improve the weakest words except by practicing them directly and individually, which is a bit tedious. Is this intentional? It seems counterproductive. If this is intentional, I suggest implementing an option that allows the user to target weakest words as before as this is far more useful.

August 7, 2013



It never has selected the weakest words for me. That's why I stopped using that feature. I just check on my own (vocabulary) or within the individual skills and practice what seems appropriate to me.


It definitely has been by weakest words for me, no question about it. For the last several months (dating back to when the last vocab strength bug fix was made which caused 2/3 of my vocab to instantly degrade to 1 bar), I check my vocabulary sorted weakest to strongest and compare it to the words selected for reviews every day. The words selected have always been my weakest words until today when it suddenly changed to the oldest of the "last practiced" column. If the apps have behaved differently for you or others, this is even more alarming in that the app behaves differently for different users.


I hadn't tried this for over a month. After your response to my post, I tried it again. And...it worked this time. I sorted my vocab by weakest words and the practice actually gave me those words. When I used to try the practice, I would keep getting sentences with 'manzana' and 'jugo de manzana' over and over...it was enough to make me swear off apple juice for life! :)


Wait, so you're saying that it's giving you words based on word strength now? I'm still getting words based on the last practiced date. Whatever broke it for me must have fixed it for you. That's kind of disturbing. Hopefully the devs will be checking into this soon. Going to submit feedback and send a direct message or two so that it doesn't get missed.


Yes. I've tried it several times since my last post and it is definitely giving me the weakest words and then removing them from my weakest words list and giving me the next weakest ones. It's great!!! I'm sorry that you are having problems but I'm glad that you posted so that I know that this great feature has started to work for me!!! Only 1 apple practice so far... :)


Hmmm... we're looking into this.

In order to investigate, I may have to "impersonate" your account and try a few practice sessions in order to see what's going on (since the practice feature is working properly for my account). Please don't be alarmed by this.

To be clear: the system is picking 4-bar words for you to practice instead of 1-3 bar words?

EDIT: OK, when all of your words are at four bars, it sometimes selects the oldest words for practice. I think this is what's happening to you, pinkodoug, because all of your vocab is at full strength according to the math. So we switch to sorting by date at that point.

EDIT2: We found the problem, it was a bug in vocab display. This has now been fixed.


Here's another update (moving the reply to this level so that it's not buried under so many nested comments).
I just completed three practice sessions with the details below:

Degraded words at the beginning of practice (all 3-bar, sorted weakest to strongest):

lengua, nariz, preparar, piedra, construir, definir, demostrar, intensidad, influencia, distribución, sombra, concentración, error, haber, sufrir, aplicar, corriendo, defender, creer, cadáver, acabar, explicar, colocar, ayudar, comentario, observar

Practice 1:

construir, definir, demostrar, influencia, intensidad, lenguas, nariz, piedra, piedras, preparar

All words that were presented were selected from the weakest list

Practice 2* :

aplicar, corriendo, distribución, error, errores, haya, hubo, sombra, sufrir

*Concentración was presented once n the practice, but missed due to a typo.

Again, all words were selected from the weakest list

Practice 3* :

rueda, pantalla, cadáver**, bomba, visitar, bola, defender**, fuente, fuentes *

*objeto was presented in the practice, but missed due to a typo ** weakest words according to vocabulary

Here's where it starts to trip up. At the time that I started this last practice exercise, 9 words were still degraded. Only two of those nine were selected from the weakest list. Most of the words were selected from the oldest of my "last practiced" list, although there was an odd exception or two (e.g. rueda was, at the time, 28th from the bottom of the "last practiced" sort order).


Yes, it's picking the oldest words from the "last practiced" field, which are all 4 bar words. Thanks for checking into it.


That would explain the problem except that it was doing this yesterday when I had ~30 words that were 1-3 bars. I practiced them each directly in order to clear them. I have 1 degraded word currently, and it's still selecting pantalón, institución, noche, adiós, día, leer, falda, suyo, feria.

ETA: perhaps this is due to a rounding issue since you say the math checks out. ~30 forms from ~1100 lemmas could be problematic. This is an issue introduced within the last few days, as previously the practice app has always selected by weakest for me even if there were only one or two degraded words - even zero on the days when I had no words degrade overnight.


We pushed a minor change that tweaks the behavior a bit. Does it seem to work better for you?


OK, since I last checked in, a few more words have degraded. Before doing a practice session, I had a total of 6 words degraded to 3 bars. This practice session selected 3 words from my weakest and 6 words from the least recently practiced. That's certainly an improvement over getting none of my weakest words, but I can't say I'm enthused about the result. Having to practice 6 words that are full strength, and that I have no need to practice, while not being given all of my degraded words sort of defeats the stated purpose of an exercise titled "practice weakest words." This is new behavior, and while the fix you pushed seems to have improved the situation, the functionality is still worse today than it was a few days ago.

I know that you have users complaining that some words are not practiced often enough (a legitimate complaint), and the changes that introduced this new behavior are probably intended to address those concerns. That's a good thing, but I think that when there are degraded words in need of practice, they should always get selected over old, full strength words. I hope you'll consider tweaking the criteria for selecting words for these practices a bit further to more consistently favor degraded words.

Thanks for checking into the problem and working to address it. It really is appreciated!


I just did another practice session, and all of the words presented were selected from the bottom of the "last practiced" column. Depending on how the math works for the selection process, that may not be very surprising given that I currently have only one degraded word in my vocab (lograr at 3 bars), which represents only about .001% of my words (.0005% of all forms). I'll let you know how things look once I've had a few more words decay.

Thanks again for looking into this issue. Your efforts are very much appreciated.

As a side note, this most recent practice included a word, el toro, that I'm sure I've encountered before, most likely during the animals section. The word, however, does not show up on my vocabulary list. I mention it here only in the off chance that it's useful.


To follow up on this issue further, I'd like to mention that things are still not working correctly (assuming that serving up exclusively full strength words in favor of weakened vocabulary is not the web app's intended behavior). As I write this, I've got 11 words that are currently degraded from full strength. I just completed several practice sessions and have only had two degraded words presented. Instead, over 50 words have been selected from my the least recently practiced list. To compound the frustration, roughly half of all practice questions involved the word "quizás", and many of the same sentence repeated. Something is certainly wonky with the selection method.

This is frustrating because, and I can't stress this enough, this worked perfectly until two weeks ago. Something changed - was it an intentional change to include words that haven't been practiced in some time regardless of their strength? Is this an unintended consequence of some other change? Regardless, the fact that it's still not working correctly is negatively affecting my, and presumably others', experience with the application. It makes reviewing words that have degraded significantly tougher because I have to practice them individually since I cannot practice them via the "practice weakest words" option (which is now a misnomer).

Is there any update to be had on the status of this issue?


OK, I looked into this. It's because all of those 3-bar words are actually 4 bars. The vocab page is lying to you!! :(

We've made several improvements to how word strength is calculated over the past few months, but apparently not all of those changes were implemented in the Vocabulary section of the website. So in effect, you're seeing old, out-of-date strength predictions, not the word strengths actually used to schedule practice.

Rest assured that as of this writing, your entire vocabulary is 4 bars. Your 4 weakest words are campeonato, cielo, pasar, and bosque, all at about 80%. :)

Now that we know what's going on, we'll try to fix this soon. (The Vocabulary page is sadly a low priority, since so few Duolingo students actually use it).


I had stopped using it because it wasn't working. But, after some recent fixes, I've started to use it every day. It is very useful now that it is doing what it is supposed to. Thanks for working on it...it's a great tool. :)


Thanks for the explanation, tatou, your efforts to get to the bottom of this are really appreciated. I think from now on, I'll start my day's Duolingo work with a practice session, and if none of my 3-bar words show up, I'll move on to other activities on the app. I'll have to tamp down my compulsive tendencies and not stress when I see a bunch of 3-bar words cluttering up my page :)


Thanks, Lyarra!

Pinkodoug: I pushed a change yesterday that should fix this problem. Let me know if lesson practice is no longer giving you your weakest words (according to the vocab page). Thanks!


Thanks for the update and continued attention to this, Tatou. I'm not sure if I understand your most recent update correctly. Should I still be seeing words incorrectly being listed as degraded on the vocabulary page?

I just did two more practice sessions. Before I started, I had 14 words degraded (3 1-bar, 11 3-bar). The words presented in the first practice were all from the weakest words list. After the first practice session, the following words were listed as degraded: luz, bosque, situación, campeonato, venir. With the second practice, the following words were presented / strengthened: absolutamente, bosque, debajo, fácilmente, luces, luz, presenta, recuerdo, supuesto, vuelve, vuelves (bold indicates a word from the weakest list). Only two of the 5 weakest words listed on the vocab page were presented, bosque and luz (also luces, the word's plural form), with the remainder of the words being selected from the bottom of the "last practiced" list. The other three degraded words were not presented.


Hmmm... I'll look at it again when I get a couple of spare cycles.


If it helps, here are some results from some practice sessions I did today. Hopefully this is useful information for you.

Earlier this afternoon (I didn't pay attention to the time, sorry), the vocabulary strength for the following words was listed as 3-bar: ruido, margen, calor, edición, preocupación, decir+prpers, piedra. One practiice session presented forms of all of these words except for piedra,. Additionally, forms of the following words from near the bottom of my "last practiced" column were presented: entrar, pesar, sentir.

At around 22:00 CDT, I did another practice session. At that time, the following words were listed as being degraded to 3 bars: pasar, piedra, campeonato, venir, reunión, mirar, comportamiento. The practice session presented none of these words, and offered the following forms of my least recently practiced words instead: baja, cabe, comienza, comienzo, culpa, depende, firma, firmas, firmo, importa, importan, respetan, respeto.

Based on these results, it would appear that there's probably still a gap between the strength at which the vocabulary display reports a word as being degraded and the threshold at which the practice scheduler considers a word to be degraded.


Do you mean it's selecting these words (pantalón, institución, etc...) again, even after you practice them?


No. Sorry, I should have been more clear. Those were the 9 lemmas selected for the last practice I did. A new practice session seems to be grabbing the next 9 from the bottom of the "last practiced" list.


I'd like to hijack this thread for a second to mention that whenever I try 'practice weakest words', it nearly always puts in the sentence 'je photographie un cheval'. Its been doing this for weeks-- even when I get the sentence right--and I'm kinda curious as to why the algorithm thinks it's so important for me to be able to talk about photographing horses.


I no longer see this feature in the ipad app. Thoughts?


It still selects the weakest words for me, as it always did...


The way I have used this requires an extra step. You first scroll down to where it shows you the words and their strengths. Usually that is only a fraction of the words you have covered. At the bottom you can click to have it show you all of the words. When it does that, it shows a button at the top explicitly to practice your weakest words.


There shouldn't be an extra step especially since what your talking about can't be done on the mobile app, where you can also practice weak words.


This feature has worked well for me in the past, but now I don't see the practice weak words feature in the ipad app. Anyone know what happened?


On the iOS app, it was removed and replaced with the duel feature, although practice weakest words is still available within each individual skill. It will be returning within the next few days - an update has been submitted to Apple and it's awaiting their approval.

Relevant threads: here and here

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