While I understand how frustrating it can be for you to have to go on the field trip, maybe you should just change your point of view. It can be a great time to spend with your child and help him in making friends. Maybe the teacher is worried about safety, for him and others. It is a huge responsibility taking students on field trips. Maybe there is an aid that could be his buddy. While this can be a legal issue, why not take a higher road in helping the school better support your child?