Treble Cat HD 1 is a free app which allows students to practice quick recognition of notes on the treble staff. Notes move across the staff and the user is asked to touch every C in 60 seconds. In this level, all pitches are labeled. The next level asks you to touch the Cs and Ds in the 60 second time limit. In this level, the Cs are no longer labeled, but the other pitches are. The labels are present until each note has been introduced. Once that pitch has been introduced, the labels disappear for that pitch. The settings allow you to choose if you would like letter labels or solfege labels. It also allows you to choose the speed of the game.
I can see some value in this game for increasing the speed in which students recognize notes. At this point, the app makes a positive chiming sound when you touch a correct pitch. I wish it would actually play the pitch you touch, a C plays when you touch a C, etc. Perhaps that is something the developers will address in a future update.
There is an in-app purchase which allows the user to upgrade to the full game for $2.99. I have not upgraded at this point and have not evaluated the paid version of the game. If you are allowing students to use your iPad, please be sure you have turned off in-app purchases in settings.
I mentioned another drill-and-practice note recognition app, Flashnote Derby, last September. This app is a better choice if you wish to limit the pitches in which you want students to focus.