I am much more concerned about the teacher in this scenario not knowing your child (regardless of his behaviour his capabilities don't change), than I am with your child... I tend to agree with HK.

Most of my son's (8) school friends are sport related not academic. This has been the case since K, where at first he seemed to have no friends or academic peers than he got involved in sport after a couple months and made heaps of friends (the cool kids no less).