Sixth grade

Sixth grade is the sixth year of schooling for students in some countries and education systems.
Afghanistan.
In Afghanistan, Grade 6 is the first year of middle school. Students are aged 11–12.
Kuwait.
In Kuwait, Grade 6 is the first year of middle school.
Laos.
In Laos, Grade 6 is the first year of secondary school.
Malaysia.
In Malaysia, the equivalent is Year 6 also known as Standard 6, as the Malaysia academic year starts in January, unlike in Europe, Canada, and the United States where it starts in August. Students will sit for an important exam called "Ujian Penilaian Sekolah Rendah" (UPSR), which translates from Malay into English as "Low/Elementary School Assessment Test", before graduating from elementary education. Standard 6 is the final primary/elementary school year before embarking into secondary /high school (Form 1). In Malaysia, primary education are commonly broken down into primary school and secondary school. There is no existence of middle school. Middle school and high school are lumped as secondary school.
Philippines.
In the Philippines, Grade 6 is the final year of elementary school.
Saudi Arabia.
In Saudi Arabia, Grade 6 is the last year of elementary school.
South Korea.
In South Korea, Grade 6 is the final year of elementary school.
Vietnam.
In Vietnam, Grade 6 is the first year of middle school.
Israel.
In Israel, Grade 6 (called Kita Vav) is the final year of elementary school.
United States.
The sixth grade is the sixth school year after kindergarten. Students are usually either 11 or 12,
though could be younger or older, if they are promoted (skip grades) or held back for not reaching a standard.
In the United States, sixth grade has been considered the last year of elementary school or the first year of middle school. In some school districts it's the last year of intermediate school. This can be seen at the local level, where adjacent districts can differ on what level sixth grade occupies. 
Students still in elementary school may continue to have a single teacher or more than one, but fewer than middle school students. However, there have been schools where fifth graders (in elementary) had five classes, and in sixth grade (middle school) only had two-eight classes/teachers who taught more than one subject. Students who attend private & faith-based schools generally remain in grammar school for kindergarten through 8th grade, then go to high school in 9th grade (as freshmen), the same as public schools.
Mexico.
“Primaria” education, in its current form became compulsory in 2009, and runs from grade one through grade six, for students aged 6 – 12 years. The Secretariat of Public Education (SEP) officially determines primary school a part of ‘Basic Education’, making it free of charge, with one year of mandatory pre-school education. SEP standardizes curriculum content for public and private schools, which includes Spanish, mathematics, natural sciences, history, geography, art, and physical education. The National Institute for Assessment of Education monitors standards and provides quality control.
Middle Education
Peru.
In Peru, grade 6 is the final year of primary school.
Uruguay.
In Uruguay, the sixth grade is the sixth and final year of primary school. Students are usually 11 1/2 years old.
Singapore.
In Singapore, the equivalent is Year 6 also known as Primary 6. They would have to take the Primary School Leaving Examination at around September to proceed to Secondary School.
During this time, students in Primary 6 would learn Algebra and 3D Shapes.