I'm from Germany. I haven't had the opportunity to spend some time in an American school, but many of my classmates did. They generally reported that the lessons were too easy, even the USA-related stuff that we don't do in that much detail over here (English-language literature & creative writing, American history, American geography...). They found it amusing that there are multiple-choice questions in tests, where you can achieve a "pass" through pure luck.
Over here, all tests require a substantial amount of writing, the only exception being fill-in grammar exercises for foreign languages. This amount of free writing might be the reason that many immigrants have trouble when joining the German school system, at first. There are integrative measures being taken, but still there's a higher percentage of immigrants going to a lower form of secondary school. Primary school is the same for everyone, but then there are 4 types of secondary school:
1) the Gymnasium, for those who had good marks in primary school. Gymnasium takes 3 years longer than the other types of schools, but in return, you get a certificate allowing you to go to any university, afterwards. If you just complete one of the other forms of secondary school, you aren't allowed to go to university, just to trade schools and the like. You can however choose to switch to Gymnasium while or after you attended a different form of school.
2) the Realschule, for those who had average marks in primary school
3) the Hauptschule, for those who bad bad marks in primary school
4) the Sonderschule, for those with learning disabilities.
Lately, Germany has also adopted the concept of a comprehensive school, called Gesamtschule. That one is supposed to put you into the right classes according to your abilities in each subject. So far, it is not very successful; a final certificate acquired at a Gesamtschule is only theoretically valued as much as the one of a Gymnasium.
Nobody forces parents to send their child to a specific type of secondary school, it is their decision. Primary school teachers are just there to give them a recommendation. That the Gymnasium isn't overrun is mainly due to: a) parents usually understand that it's better for the child to be in an environment where it's at least average in class and where teachers explain things as often as necessary; rather than one where it constantly has to strive to keep up; b) if your marks are too bad, you have to repeat a year. You can't repeat the same year twice and you can't repeat more than 3 years total, so if, after a year of repeating, your marks still aren't good enough for a "pass", you are sent to a different type of school.
I think this division into different types of secondary school is a good idea, because it means that classes are more homogenous and there are therefore less bored people and less people slowing down the class by asking things that everybody else understood. Also, it allows for a differentiated lesson plan: the Hauptschule and Realschule teach more practical-oriented stuff for example, whereas the Gymnasium also teaches skills that are necessary at university. For example when introducing a new formula in maths, Hauptschule and Realschule would just teach you to use that formula in everyday applications, whereas the Gymnasium would also teach you how to derive it, why it is the way it is. Also, the requirements of foreign languages are different at these types of school: in order to complete Hauptschule or Realschule, you just need to know one foreign language; for Gymnasium you have to know at least two, and have taken classes in them for at least 9 and 5 years. It is possible to do a little detour via the Realschule around the time the second foreign language is introduced, which allows you to start learning a second foreign language only in grade 11, so that you'd learn the second foreign language for just 3 years, rather than 5. But this doesn't really make a difference because the foreign language starting in grade 11 is usually taught in a very compact manner, e. g. I took Italian at that stage and three years afterwards, the course was able to converse about the ecological problems of Venice, the reasons for the acqua alta (frequent high water flooding the town), the problems of mass tourism etc. in Italian.
For particularly gifted kids, there is the possibility to start university while they haven't yet finished Gymnasium. Also, there's a foundation that gives extra seminars for them, though not very often and not for the masses.
@Hunter: aren't you confusing the Netherlands and Germany? Our school systems are quite diverse...
Just my two cents
Judith