Duolingo hosted a global competition in predicting future mistakes that learners of English, Spanish, and French. Sana Labs won all language categories on all benchmarks.
globally at predicting future mistakes of language learners

Our solutions won all categories in Duolingo's global AI personalization for education competition in preciting future mistakes of language learners.

milliseconds to give feedback on pronunciation

Sana Voice scores a learner's pronunciation of a sentence. Pinpointing individual phoneme-level mistakes and providing feedback for improvement. Try it!

mistakes of learners correctly predicted (AUC)

Sana Learns models knowledge acquisition within all subjects, allowing for timely personalized intervention.

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"Using Sana Labs' machine learning platform we were able to transcend the limits of traditional approaches"

State of the art modeling of language learning for Duolingo.


Duolingo is a global language learning company with over 300 million students.


Students create immense amounts of data on their various mistakes. The goal of this work was to predict future mistakes that learners of English, Spanish, and French will make based on the mistakes they have made in the past.



In analysing student mistakes, their knowledge gaps can be detected. Sana Labs used an ensemble approach that did not require encoding domain knowledge and can capture more nuances of learning. For example, the student below seems to be struggling with "my", "mother", and "father." These mistakes could point to difficulties with possessive pronouns or the orthography of English "th" sounds. The Sana model picks up on these trends, predicting student knowledge gaps in a personalized way that evolves over time. These predictions can subsequently be used to personalize learning by recommending exactly what to study and when, based on each individual's needs.


The Sana technology performed extraordinarily well, and made the most accurate predictions. The Sana technology also produced the best evaluation metrics on Duolingo's benchmark.