1. An information processing apparatus for outputting a content created in a language to learn, comprising: a receiving unit configured to receive an input operation; a recording unit configured to associate a vocabulary with a difficulty level determined for each vocabulary, and configured to store the vocabulary and the difficulty level, the vocabulary including a word, an idiom, or a phrase consisting of two or more words in a language to learn; a registration unit configured to register a learning level, which is a degree of learning of the language to learn of a learner; calculating unit configured to calculate a frequency in use, which is the number of the vocabularies to learn used in the content; a specification unit configured to specify, according to the calculated frequency in use and the registered learning level, and among the vocabularies of the language to learn used in the content, a vocabulary which is an object to learn as a vocabulary to learn; and a control unit configured to cause an input operation received by the receiving unit during an output of the content to be registered as an input operation in response to the output of the vocabulary to learn.