This is possibly a good long term approach, but what to do when you need to put the situation under the control quickly, and kids just don't cooperate? I had such experience when my 4yo kid was at some point fascinated by kitchen stove, turning the gas knobs on/off. It's just something that you can't slowly teach him not to do, you need to draw the line right away, for his own safety. You can't reason with kid that small, and it's too dangerous to let him learn the lesson by trying, so you just have to scare him out of it.