English Grammar Adaptive Test - Learn from personalized recommendations with LinguaLeo

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    One of the main tasks that LinguaLeo sets for itself is the personalization of the service, which allows you to make learning English more effective. An important achievement along this path was the launch of the adaptive test on the LinguaLeo service. In a post we will talk about what kind of test it is and how we developed it.



    What is an adaptive test and why is it needed

    The adaptive test provides speed and accuracy that cannot be achieved with traditional testing methods. This is a test that "adapts" to the user, complicating the questions if the user answers correctly, and simplifying if he is mistaken. Thus, the test person does not need to answer questions that do not correspond to his level, and the number of tasks can be reduced to 60% without loss of quality of the result.

    Adaptive testing is one of the primary elements of the created “smart” training system that will “know” the user and will offer him the training materials that suit him in terms of complexity.

    The adaptive test LinguaLeo is fixed in the personal tab “ Home”, According to the test results, the user is offered courses that are most appropriate for his level:

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    The test can be passed in several stages without losing results:

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    Technology

    It took several months to develop, the main difficulty was creating a “knowledge tree” of English grammar (a hierarchical structure that reflects our understanding of the relationship between the grammatical phenomena of the English language and their relative complexity for learning). There were problems both in the “tree” itself, and in the test generation algorithm, task sequence, evaluation of the test result (the latter is still being finalized by the LinguaLeo team).

    The hierarchical structure that LinguaLeo uses to model English grammar is a directed graph. At the top of the graph are “grammar tags” - units of English grammar (and sometimes vocabulary): tenses, types of sentences, use of prepositions, phrasal verbs, etc. The edges of the graph are the relationships between grammatical phenomena. For example, Present Perfect Continious depends on Present Perfect and Present Continious, which in turn depend on Present Simple.

    To create an adaptive test, the LinguaLeo team prepared a question for each tag. Then, an algorithm was developed that offers the following question, depending on whether the user answered all the previous questions correctly or not. This algorithm takes into account the relationship between the tags in such a way as to obtain the maximum amount of information about the user's knowledge for the minimum number of questions. If the answer is incorrect, the algorithm goes “down” the graph, i.e. to the tag on which the tag of the current question depends. With the correct answer, we move on to the next group of questions.

    Thus, the adaptive test is a binary tree. In order to optimize performance, this tree was calculated in advance. The algorithm is implemented on scala, and the tree itself is saved to a table in mysql.

    The full English grammar graph according to LinguaLeo looks like this:

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    And here is a fragment:

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    Future plans

    In the near future, LinguaLeo plans to add a vocabulary test (so far only grammar is being tested). The adaptive test will become even more flexible, with various options for tasks.

    Check out LinguaLeo , take an adaptive test and learn English in a personalized way!

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