shape train preschool

Can anyone give me some suggestions on toilet training?
My son is 4 and still has "accidents" several times a week. We have tried to reward him when he uses the bathroom, let him choose his new underwear, leaving him to choose a urinal, and punish him as he goes in his pants. His preschool even said you can not return to class unless it improves. This is a very smart kid (he knows his numbers, colors, letters, shapes, etc.) that is very well in school and has many friends, but I am beginning to wonder if something is wrong with him. The child is 3, I wear diapers, but never had so many problems. Please help!
My daughter is 4 and we have tried everything – even a class called Boot Camp. Many things have helped, but nevertheless, sometimes we fight – that goes in phases. The last straw for me was just putting his hands full. I told her she is responsible for your bathroom. My husband and I explained that I do not tell others when they go, so do not will tell you when to go. Thus, no accidents have other consequences than it has everything to do cleaning at home. It got worse at first, but eventually improved. I would like to have a more magical – it really struggled. I send him to "regular" as times before leaving the house before going to bed, and in the morning. Of course, not verbally praise good behavior as the key is not able to detect disappointment or anger when they have "accidents". Good luck!
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