Methodology: creating and testing the dictionary

To create Learn These Words First, the 2352 definitions in the NSM-LDOCE dictionary were sequenced into layers using the recursive-dependency statistics from the "Non-Circular Dictionary" study. Then each definition was edited for greater fluency and precision, utilizing words available in the preceding layers.

Using computer-aided paraphrase, the number of "semantic molecules" was reduced to around 300 words. These words, preceded by the NSM vocabulary, were grouped into 12 lessons and expanded to use full-sentence definitions and examples.

Student participants performed headword-identification tasks to evaluate the quality of every definition in the Learn These Words First lessons. For fill-in-the-blank tasks (given definitions without headwords), students correctly identified the missing headword 95% of the time. For complete-the-word tasks (given definitions and only the first letter of each headword), students identified the headword 100% of the time.

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