13. A system comprising: a keyword store configured to store a plurality of keywords extracted from one or more resources and metadata associated with each respective keyword, the metadata associated with each respective keyword indicating a word difficulty score of the respective keyword; a computer comprising a processor and non-transitory machine-readable storage instructing the processor to execute the steps of: automatically selecting from the keyword store a set of one or more keywords based upon the word difficulty score of each respective keyword and one or more skill scores of a learner-record stored in a learner database; identifying in one or more dictionary sources, one or more distractors that are of one or more distractor types and are associated with a keyword; identifying in the one or more dictionary sources a plurality of words having an edit distance based upon a keyword, wherein the edit distance of a word is an amount of letter-insertions and letter-deletions required for the word to be the keyword; generating a set of one or more identified orthographic distractors comprising one or more words of the plurality of words, wherein the edit distance of each respective word in the set of orthographic distractors satisfies an edit distance amount setting, and wherein the edit distance amount setting limits the edit distance of the respective word relative to the keyword based upon the one or more skills scores of the learner-record; generating a set of one or more identified semantic distractors comprising a synonym and an antonym of the keyword; and identifying a context of the keyword according to metadata associated with the keyword identifying content of the resource, wherein the semantic distractors are identified based on the context of the keyword in the resource.
13. A system comprising: a keyword store configured to store a plurality of keywords extracted from one or more resources and metadata associated with each respective keyword, the metadata associated with each respective keyword indicating a word difficulty score of the respective keyword; a computer comprising a processor and non-transitory machine-readable storage instructing the processor to execute the steps of: automatically selecting from the keyword store a set of one or more keywords based upon the word difficulty score of each respective keyword and one or more skill scores of a learner-record stored in a learner database; identifying in one or more dictionary sources, one or more distractors that are of one or more distractor types and are associated with a keyword; identifying in the one or more dictionary sources a plurality of words having an edit distance based upon a keyword, wherein the edit distance of a word is an amount of letter-insertions and letter-deletions required for the word to be the keyword; generating a set of one or more identified orthographic distractors comprising one or more words of the plurality of words, wherein the edit distance of each respective word in the set of orthographic distractors satisfies an edit distance amount setting, and wherein the edit distance amount setting limits the edit distance of the respective word relative to the keyword based upon the one or more skills scores of the learner-record; generating a set of one or more identified semantic distractors comprising a synonym and an antonym of the keyword; and identifying a context of the keyword according to metadata associated with the keyword identifying content of the resource, wherein the semantic distractors are identified based on the context of the keyword in the resource. 20. The method according to claim 13 , further comprising: receiving, from a software module, a request for a set of distractors of the distractor type and associated with a corpus of a new activity; and outputting, to the software module, the set of distractors requested.