Many times students will struggle with certain notes, but those notes are not always in the music they are playing at the time. Flash cards are great tools, but sorting them out at every lesson can become a hassle. So index cards that are spiral bound for each student becomes a great solution.
First I find out what notes the student is struggling with by asking them to name the note as fast as the can. I only give them a couple of seconds, because I want them to instantly know the note. I also ask them to play the note in the correct place on the piano. The notes they have trouble with go in the Drill Book.
Then at every lesson I ask them to name the note and play it. If they do it correctly, they get to put a sticker on the card. When they get ten stickers, they have successfully learned the note.
I have my students participate in the One Minute Club, so any notes they miss while doing this exercise also go in the Drill Book. Any new notes we learn can be added as well.
I use the Drill Book for chords and keys. You could even use it for rhythms, intervals or vocabulary words.
You can keep the books safe in the studio or send the books home for the students to practice with.
You can find a set of 36 spiral index cards at Amazon for $28.39 which ends up being .79¢ each if you get free shipping.