Piano hacking

Here's a plus side to not owning a real piano - you'd NEVER do something like this to one!  In one of our stacks of teachery stickers from the dollar store (in the school supplies section) I found these two thumb stickers.  How perfect is this for middle C position??  Where do the thumbs go?  On the thumb, woohoo!

Also, I used a dry erase marker when we first started to name some of the notes, but I kept losing it.  But we always have crayons everywhere - and they rub off cleanly on their own, or with a little Windex.  So now at the beginning of a lesson, WonderGirl gets the job of writing the names on the notes. It's good practice, and she gets the thrill of doing a little mom-sanctioned graffiti.  Do you have any hacks for the piano?