Plastic door knob

Ever since my son learned how to turn the door knob especially in our bathroom I decided to purchase a plastic door knob. Now, since I put those plastic door knobs he can’t get it to our bathroom anymore. Before I always spank his hand because he when he gets inside the bathroom he will put everything reachable inside the toilet bowl. It’s really upsetting and I was fed up with him doing the same thing. He tries to open the door but unfortunately he couldn’t do it anymore. Tough luck son! For those parents out there who went through with the same situation as i did, i would recommend you to get a plastic door knob, you can get it at wal-mart and it's very affordable.