Also, in addition to contacting the school/teacher, I would also want to mention that most middle schools (and high schools for that matter) allow the parent to put the child in a higher level than they may test into or qualify for. I don't usually advocate this because it often is a case of parental wishful thinking, but if your child doesn't place where you think he should be due to the discrepancies of being taught in Europe vs. the US, then it might be something you would want to look into.
M, mommy to A 2005, E 2007, and L 2010