Germany does not only have on high school but three different high school (or secondary school) pupils attend.
After primary school teachers give a recommendation which school is most suitable. The schools differ in difficulty. Students who are good in learning will attend a more challenging school, while students who are slower in learning will attend more easy to follow classes.
The types of schools are das Gymnasium, die Realschule and die Hauptschule.
Das Gymnasium – This is the most challenging secondary school. Students will learn high level concepts and discuss a wide range of topics in class. Usually Gymnasium takes 8 or 9 years. After Gymnasium students have the qualification to attend any university in Germany. Most students attend Gymnasium these days as its necessary for many jobs.
Die Realschule – Realschule takes six years. It qualifies students for to be able to learn a range of jobs. After attending Realschule for six years students can attend further specific schools that prepare for a certain kind of job (die Ausbildung, the apprenticeship).
Die Hauptschule – If students find learning challenging, they will get special attention in Hauptschule. The things taught at Hauptschule tend to be more practical and applied. It takes five to six years, afterwards students are ready to learn how to do a specific job in an apprenticeship or Berufsschule (vocational school).
As the education system in Germany is organized by states this types of schools differ from state to state. Some states do not have all types of schools or they have schools were all students study together. These schools are called Gesamtschule (die, integrated school).