A reading device, such as a mobile tablet, may download an electronic reading material, such as a textbook, to local memory. The reading device may store a reader profile representing one or more aspects of a user's reading ability. The reading device may convert the downloaded reading material using the reader profile to better conform to the user's reading ability. As the user reads reading materials using the reading device, the user may provide feedback as to portions of text in the reading materials, including whether a word is not recognized, whether a grammatical construction is confusing, etc. Using the received feedback, the reading device may modify the reading profile to further improve the degree to which it represents the user's reading ability. Once modified, the reader profile may be used to re-convert already downloaded reading materials or to convert subsequently downloaded reading materials.