11. The computer program product of claim 8 , further comprising: program instructions that are stored on at least one of the one or more storage devices and that, when executed by a processor, associate, with each vocabulary word in the plurality of vocabulary words, a value indicating a likelihood that the vocabulary word associated with the value will appear in a question.
11. The computer program product of claim 8 , further comprising: program instructions that are stored on at least one of the one or more storage devices and that, when executed by a processor, associate, with each vocabulary word in the plurality of vocabulary words, a value indicating a likelihood that the vocabulary word associated with the value will appear in a question. 14. The computer program product of claim 11 , further comprising: program instructions that are stored on at least one of the one or more storage devices and that, when executed by a processor and in response to determining that the values associated with the plurality of vocabulary words equal a pre-determined value, indicate that the chapter is completed.