文獻指出以英語做為外語學習者在接觸學術英文聽力（如大規模開放式線上課程）時，常面臨的一項挑戰是單字量不足，除此之外，對於專業單字不熟悉也是影響學術聽力理解的原因之一。因此，本研究旨在透過(a)計算 Coursera大規模開放式線上課程的詞彙覆蓋率與(b)計算學術口語詞彙表對於 Coursera 大規模開放式線上課程的詞彙覆蓋率，探討理解 Coursera 大規模開放式線上課程所需的單字量，以及其學術口語單字檔案。
研究結果顯示要達到 95%的詞彙覆蓋率，需要 3,000 個字彙量加上專有名詞、邊際詞彙、複合字以及首字母縮略字；而要達到 98%的詞彙覆蓋率，則需6,000 個字彙加上專有名詞、邊際詞彙、複合字以及首字母縮略字，然而，不同領域所需的單字量有所不同。至於學術口語詞彙的整體覆蓋率，學術口語詞彙表（Dang, Coxhead, & Webb, 2017）覆蓋了 90.77% 的 Coursera MOOCs 語料庫，然而，ASWL 在各領域的覆蓋率並不相同。上述發現表明，以英語做為外語學習者需要掌握 3,000 到 6,000 個詞彙以及專有名詞、邊際詞彙、複合字和首字母縮略字，才能充分理解 Coursera 大規模開放式線上課程。研究結果還表明，學習學術口語詞彙表有助於學術聽力理解，因為學習者在聽 Coursera 大規模開放式線上課程時很可能會遇到學習學術口語詞彙表中的詞彙。根據以上的發現，本研究亦提出英語教學上之意義探討。

Studies have found that the common challenge that EFL (English as Foreign Language) learners face when listening to authentic academic English materials, such as MOOCs, is a lack of vocabulary. Moreover, unfamiliar technical or specialized vocabulary can be a factor affecting their listening comprehension as well. Therefore, the present study aims to investigate the vocabulary size needed for adequate listening comprehension and to determine the academic vocabulary profiles of Coursera MOOCs by (a) measuring the lexical coverage of the Coursera MOOCs, and (b) determining the coverage of academic spoken vocabulary in Coursera MOOCs.
The results show that, in general, it requires 3,000 vocabulary knowledge plus proper nouns (PN), marginal words(MW), transparent compounds(TC), and acronyms(AC) to reach 95% coverage of the Coursera MOOCs corpus; to reach 98% coverage, it requires 6,000 vocabulary knowledge plus PN, MW, TC, and AC. However, the vocabulary size needed for each discipline differs between fields. As for the coverage of academic spoken vocabulary overall, the Academic Spoken Word List (Dang, Coxhead, & Webb,2017) covered 90.77% of the Coursera MOOCs corpus. However, the ASWL coverage is not evenly distributed across fields. The above findings indicate that EFL learners need to acquire 3,000 to 6,000 vocabulary plus PN, MW, TC, and AC to have adequate comprehension of the Coursera MOOCs. The findings also suggest that studying Academic spoken Word List is beneficial for academic listening comprehension because it is highly likely that learners encounter the ASWL vocabulary when listening to Coursera MOOCs. Pedagogical implications have been discussed based on the findings.

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