New app for intermediate learners: Practice vocabulary through sentence writing

Hey everyone,

I've been working on something that addresses a problem I kept running into as an intermediate learner: I could recognize vocabulary in context, but couldn't actually use it naturally in my own sentences.

What it is: SentenceLab is a vocab practice app that focuses on sentence creation instead of flashcards. You pick vocabulary words you want to learn, write sentences using them, and get instant AI feedback on correctness and naturalness. The app uses spaced repetition to bring words back when you need to practice them again.

Who it's for: HSK4-6 level learners who are tired of passive review and want to practice actually using vocabulary in context.

Why I built it: I found that writing sentences forced me to really understand how words work - their collocations, when they sound natural, grammar patterns, etc. It's a lot more active than recognizing a word on a flashcard. I wanted a tool that would give me feedback on my sentences the way a language exchange partner would, but available anytime.

The app is live now at https://www.sentencelab.ai. It's free to try it out.

Would love to hear what you think, especially if you've been looking for ways to move beyond passive vocabulary review.

Looks interesting. I'm going to sign up for the free trial tonight and will give you some feedback in a few days.

Thank you! I’m actively working adding new features and fixing bugs, so keen to hear what users are thinking! 

I've used the app for a week now. I like it! The problem you speak about, I also have - lots of words I understand but not confident in using myself. I'm Hsk 5-ish btw. I used to use a flashcard app for vocabulary, but haven't for the last couple of years. I agree this is better than just recognizing the word on a flashcard. I don't have much to criticize or give feedback on. One thing I will say is I'm not sure about the sentences highlighted on these screenshots which appear every time you submit an attempt, what's your logic behind including these comments? I couldn't really think of too many ideas of things/functions to add to the app. It would be cool if there was a way to add grammar structures as well as vocabulary. Also, sometimes I simply can't think of a sentence, even if I know how to use the word. Maybe if the was a way to request a topic to write about or sentence to translate. Let's say the word was 风格 and I can't think of what to write a sentence about, I could ask for a suggestion and it would tell me: Use 风格 to talk about "music" or something. Or ask it to randomly generate a sentence in English that would call for 风格, like: "Tsingtao produces many styles of beer, which do you prefer?". Just an idea. Also, what happens when you master a word? Will it still come back every so often? Overall, I think the app is a useful way to help move vocabulary from passive to active. I'd like to continue using it. What are you charging for the subscription?

Sorry thought I replied to this, turns out I forgot to hit send!

That’s great feedback thank you!

The idea behind the those sentences that appear on the feedback is that sometimes you’ve used the target words correctly but the sentence has some issue somewhere else unrelated to the target word. Those issues should appear in that extra box, but perhaps it’s not clear right now - I might remove it until it’s a bit more polished.

Good idea about grammar and having some kind of writing prompt when you can’t think of a sentence - I’ll think about how to implement them.

When you master a word, it will be scheduled for review once a month. I might make this configurable in the settings so users can change the review frequency.

In terms of subscription pricing, I recently added a pricing section to the homepage - apologies that was missing originally!

So what I've done when I can't think of an idea for a sentence is just set up a thread in ChatGpt to give me a sentence, then I translate it or modify it in Sentence Lab. 

I’ll integrate something like that directly into SentenceLab for you!

Spotted a problem: I had 3 custom lists under custom collections, but 2 of them have disappeared. The words are still in the system, but the lists are not.

Edit:

@jxw125 has already fixed this, thanks for the quick action

@suMMit I've added an initial version of the writing prompt feature. For now, the writing prompts are all English sentences that can be translated using one of the target words. For now, the prompt asks users to 'Use 1 or more of the target words to translate the below', instead of 'Try using 风格 to translate the below' - since I thought giving away which target word should be used to translate the sentence might be a bit too 'easy'?

Subsequent versions could add other types of prompts that you suggest, like questions or topics to write about.

Hi @jxw125, this is a great project! Do you mind me asking how long this took you, as well the workflow for accomplishing something like this? A couple months ago I wanted to do something similar, I first made a little chrome add on implementing a hover to see pinyin function, but got stumped trying to use baidu translate api and gave up.

On 12/10/2025 at 11:06 PM, jxw125 said:

I’ll integrate something like that directly into SentenceLab

I've been testing it and it's a great addition! What I've been doing is writing sentences of my own idea for each word that I can, and then the words that are leftover and I can't think of how to use them or what to write about, I click on the "light bulb". I then either translate the sentence given or use it as a springboard and customize it more to myself. It's worked well so far. 

I see you've re-designed the view vocabulary list feature. It used to be that on that list you could delete words you decided you didn't want to study anymore, now you can't do that. While I think the list looks nicer now, I liked to be able to delete words. Sometimes I add a word and after making a few sentences I decide it's not really that useful(or at least not right now) and I'd just like to get rid of it. 

Ah good spot, I missed that from the redesign! I’ll aim to add it back by the end of tomorrow.

@suMMit you can now remove words from a vocabulary list again. Hopefully it's intuitive, but if you click any word card inside a given vocabulary list you'll see a "Remove from list." button. When clicking, you'll be asked to choose between:

• Remove from list only - Keeps your progress and scheduled reviews (good for reorganizing)
• Pause reviews - Removes the word from the list and stops scheduled reviews but saves your stats (good for words you're not ready for yet)

Your progress is always preserved for now, but I'm planning to add a full word detail page soon that will have a way to permanently delete a word if needed.

Thanks again for the feedback, keep it coming!

That update is working well.

I had an idea, what if you could click and get a list of common collocations for a particular word?

It's a great idea, but the challenge will be sourcing the underlying data that can power it.  As a small workaround, I recently added a 'previous sentences' section to the word popup that shows you sentences you have written in the past which gives a small insight into possible collocations - but only ones you have used. Perhaps as more users start using SentenceLab you could have insight into ways other people are using a given word (provided they opt in to sharing this of course), but it might take a while for the community to be big enough for that. For now third party data is probably the best option which I will need to research further.

Unrelated, I changed the URL from sentencelab.ai to sentenelab.io because there seems to be a lot of ai fatigue right now. People were not willing to try SentenceLab just because it had ai in the website name - hopefully this change reduces some of people's initial skepticism. There should be no impact on existing users, you should be redirected to the new URL automatically.