Secondary schools typically follow on from primary schools and lead into vocational and tertiary education. Attendance is compulsory in most countries for students between the ages of 11 and 16. The organisations, buildings, and terminology are more or less unique in each country.
Within the English speaking world, there are three widely used systems to describe the age of the child. The first is the 'equivalent ages', then countries that base their education systems on the 'English model' use one of two methods to identify the year group, while countries that base their systems on the 'American K-12 model' refer to their year groups as 'grades'. This terminology extends into research literature. Below is a convenient comparison 
School building design does not happen in isolation. The building (or school campus) needs to accommodate:
Each country will have a different education system and priorities.  Schools need to accommodate students, staff, storage, mechanical and electrical systems, storage, support staff, ancillary staff and administration. The number of rooms required can be determined from the predicted roll of the school and the area needed.
According to standards used in the United Kingdom, a general classroom for 30 students needs to be 55 m², or more generously 62 m². A general art room for 30 students needs to be 83 m², but 104 m² for 3D textile work. A drama studio or a specialist science laboratory for 30 needs to be 90 m². Examples are given on how this can be configured for a 1,200 place secondary (practical specialism). and 1,850 place secondary school.
The building providing the education has to fulfil the needs of: The students, the teachers, the non-teaching support staff, the administrators and the community. It has to meet general government building guidelines, health requirements, minimal functional requirements for classrooms, toilets and showers, electricity and services, preparation and storage of textbooks and basic teaching aids.  An optimum secondary school will meet the minimum conditions and will have :
Government accountants having read the advice then publish minimum guidelines on schools. These enable environmental modelling and establishing building costs. Future design plans are audited to ensure that these standards are met but not exceeded. Government ministries continue to press for the 'minimum' space and cost standards to be reduced.