D.J.
Hi Lei,
Your son is just getting familiar with his body parts and theirs functions. It is a whole new big world for him and there are so many things there to be discovered and so many limits to be checked, and so many borders to be pushed. Plus about this age the testosterone is starting to hit and than you end up not knowing who you are dealing with. But this is a different story... Now about the poop. Try to think from his perspective - if he sits down for 5 min and draws a picture, doesn't matter how bad it is, you do get excited, you are telling him "good job", you are so proud with him, you hang it on the refrigerator, you are showing it to all the family members, even the dog and the cat, and it is such a big deal and one way or another he gets rewarded for that! In short - he produced something and it looks like everybody is very happy about it! And than he knows what you are expecting him to do in the potty, and he sits down and work hard for 5 min and you probably make funny faces because of the smell and than simply flush "his production" in the toilet. This is the part he doesn't understand and he needs you to help him understand it. In his world everything he does should be a big deal and you need to acknowledge it and price him. Next time he does it somewhere else, do not make a big deal out of it, because he might learn that it could be one of the ways to get mommy's attention, even if it is negative, they love it anyway! Simply say something like: "I saw you pooped in your bag. We don't do that. We poop in the potty! May be next time you should try to do it there." And when he goes and poops in the potty make a big deal out of it. And don't be in a rush to flush it down. Talk about it, sing a "bye-bye, poo-poo" song or anything, just let him know that you know he worked hard on this "project" too and he did a good job! I hope I was helpful. Let me know if you need to know more. Good luck!