That sounds strange that the preschool allows children to not participate during learning time. I have never heard of anything like that before. While learning the abc's and counting in preschool is great and pretty much the norm, it is more about learning how to follow directions, participate in groups and learning, play with other kids, share, etc. Maybe you might want to consider a more structured preschool program that incorporates both free time and required learning time, and one that engages the children. Also, another thing you can do yourself is go to your local library or purchase any/all of the Leapfrog videos. Our library has at least three or four of them. Maybe rent one every week and then start over when you are finished to reinforce. They were a tremendous help in teaching my son some of the basics and watching them was more fun than it was work!
Here is a link for more info on those:
http://shop.leapfrog.com/leapfrog/jump/Learning-DVDs/cate...
You might also want to sit your son down and ask him some open-ended questions about school. Maybe you can get to the root of the issue: Does he not like the teacher? Is it how learning is approached? Is it too boring to sit for long periods of time? Learning about how your child learns best will be an invaluable tool throughout his educational career! Good luck!