I was letting her use my pc to use the internet (she is 13 now, was 12 then) and I caught people taking advantage of her. I installed a key press tracker and talked to her about internet safety. Of course, she didn't listen, so I told her she wasn't allowed on my devices anymore. A few weeks later I logged onto my laptop and saw she'd been on it every day before I got home. At that point I told her about the keylogger and she was too mortified to try it again.
I love that girl, and I hope she will understand why I acted so harsh about it when she is older.