Moreover, Ogden assumed that any student should already be familiar with (and thus may only review) a core subset of around 200 "international" words.[7] Therefore, a first-level student should graduate with a core vocabulary of around 1200 words. A realistic general core vocabulary could contain around 2000 words (the core 850 words, plus 200 international words, and 1000 words for the general fields of trade, economics, and science).