@ AviraDeArah I don’t think anyone is saying that the boys are not bright. The question is that since the state has a legitimate interest in an educated citizenry, what is an objective way of determining that they are receiving a basic education.
Regarding the language issue, some Amish operate their own schools where instruction is completely in Dutch / German. Others send their children to the local school district, which finds and hires teachers that speak Dutch / German, and work with the Amish community to create an acceptable curriculum As I mentioned, the Amish argued and won in the Supreme Court for their children to leave school after 8th grade
The Amish are firm in their religious principles and fought for what mattered most to them, but otherwise adhered to their responsibilities under the law.
There is precedent for finding accomodation for a religious community.