Does he yell at all his teachers or just some. Has he been yelling all year? Did he have these problems in 7th grade? What subjects are his worse grades in and were they the same subjects as last year?
Summer camp is usually a good idea for any kid.
His ideas sound fabulous - a boy's summer camp, or a military school sound like great ideas.
Are you opposed to sending him?
Does he explain why he is yelling at the teachers, how do they handle it ? How is his home life , has he got friends ,are they good sorts , does he do any sports ?.If he wants to go to summer camp, military school it may help him .Have you talked tio him asked him how he feels if there is any problem you are not aware of ?