Automatic clozing and word clozability
If you don't pick a word to cloze when creating a flashcard, then the clozed word will be chosen automatically during a lesson.
When choosing which word to cloze, Mandarin Mosaic takes into account a concept called Word Clozability.
Word clozability is defined as: "Given that a user knows a certain word, how often on average do users get that word correct when it is clozed in a sentence that they haven't seen before?"
Using this measure, it becomes clear that some words are better for clozing than others. For example, if a word has many synonyms then it is usually not a good word for clozing. Conversely, words that have few synonyms often have a high clozability score.
Mandarin Mosaic will prefer to cloze unknown words or words which are intended for review in a word review lesson, but if those words have a low clozability score, then occasionally a different word in the sentence will be chosen for clozing.