ML and SL are powerful and programmable calculators.
Use SpeakTextMultiVoice to get written text spoken with multiple voices. It will make an excellent tool for those teaching or learning the English language.
Use Lexical to harvest English words from websites. Lexical can also be used to quickly look up English words from the built-in dictionary on your iPad, without access to the Internet. Lexical will make an excellent tool for those teaching the English language and for those learning it and also for those who want to broaden their English vocabulary.
Use RadixJam to learn how to represent numbers in different bases. RadixJam will make an excellent tool for those teaching or learning mathematics or computer programming.