3 year old, Bowel Movements

My three year old has been potty trained completely for a few months.  Just recently he has started pooping his pants when he is at preschool while he is out playing.  He has no problems at home and typically has a bowel movement every other day.  When he does poop his pants at school, he will lie to the teacher about doing it or blame it on another kid.  In the last three weeks he has pooped his pants twice a week at school.  Each time has been while he is on the playground.  The teachers make him try and go before he goes out to recess, but he never ends up going.  I'm not sure what to do and I'm getting afraid that they aren't going to let him come back since he needed to be potty trained in order to attend the school.  Any suggestions??

[Kevin Kennedy, Ph.D.]

As you can see, he is not completely potty trained, but he is on his way. Now, it may be that he is reticent to use the bathroom at school. Does that seem to be the case? From a management point of view, it's OK if the teachers tell him that he won't be able to go outside if this continues. It may motivate him to use the bathroom in school.