A personal electronic device is adapted to construct data tables from user input received over time relating to translations of translatable items from a first language to a second language. Entries in a data table for a user are dynamic and may indicate likelihoods of the user correctly translating translatable items as a function of time. Each translatable item may have a different time-dependent likelihood of a correct translation. Operation of the personal electronic device for a user may be based in part on the acquired, time-dependent likelihoods for that user, so that information may be presented to the user in a more efficient manner.