1) Build a Word Easy Spelling learn to spell sight words, long and short vowels--with 700+ words, students can choose to learn, practice or test. The app keeps a history of the students progress. You can use upper/lower case letters as well as toggle audio feedback on and off. ($2.99)
2) Build a Word Easy Spelling with phonics--same capabilities as the previously listed app with more emphasis on phonics. Toggle on audio and/or visual prompts. ($2.99)
3) Build a Word Express--this is the free version that allows a lot of the similar functionality as the other apps but there are in app purchases needed in order to reap the whole benefits of this great app.