I can relate to this, because I've tried something similar. I used to zap my little one for books. In your case, I love the fact they are paying you back in sats for things they want at a store. There's so much educational value to it!

My challenge, and the reason I stopped, is that I couldn't tell if my son was reading because he understood the validity and importance of it, or just because of the sats? In other words, I wasn't sure if he would have still continued if I had run out of sats...