It can prove difficult to estimate its own vocabulary capacities in a foreign language. It can also be difficult to find which words are still missing to its own knowledge: there is a need for targeting the words which are the most useful in the foreign language.

One can find frequency analysis of text corpuses (or "corpora" for pedants) online for instance on the Wiktionary project, originating from the Project Guteberg which works on a collection of public domain books. The words are ordered by frequency, and one can browse the list in order to find the first words we don't know — yet. Once discovered, these words can be added to flashcard-type learning softwares — these flashcards could even be provided pre-built so that adding one is easier.

One can then evaluate its own vocabulary level to the number of most-used words known.

Instead of working on a student-class level, this personalized method looks like one of the best complementary method for brute-force vocabulary upgrade. Though for the classroom it can set student level targets.