<P> In the United States (U.S.), the grades traditionally begin at 1 and run to 12; they are referred to by ordinal number (e.g. first grade, or 3rd grade to 12th grade). An additional preceding level called kindergarten ("K") is now standard in most areas, and a further preceding level called preschool education or nursery school is not uncommon . In some parts of the state of Wisconsin, kindergarten is split further into junior and senior kindergarten . </P> <P> Before the term "middle school" became much more commonly applied, grades 7--8 were placed in "junior high school" (with grade 6 in some schools). </P> <P> At the secondary school level ("high school"), grades 9--12 are also known as freshman (or "first - year"), sophomore, junior, and senior . At the post-secondary level (college or university), these terms are used almost exclusively to refer to what would otherwise be grades 13--16, ending denoted as "college senior". Then come post-graduate levels . </P> <Table> Table US: Ages in grades <Tr> <Th> Ages </Th> <Th> Year </Th> </Tr> <Tr> <Th_colspan="2"> Elementary school </Th> </Tr> <Tr> <Td> 5--6 </Td> <Td> Kindergarten </Td> </Tr> <Tr> <Td> 6--7 </Td> <Td> First grade </Td> </Tr> <Tr> <Td> 7--8 </Td> <Td> Second grade </Td> </Tr> <Tr> <Td> 8--9 </Td> <Td> Third grade </Td> </Tr> <Tr> <Td> 9--10 </Td> <Td> Fourth grade </Td> </Tr> <Tr> <Td> 10--11 </Td> <Td> Fifth grade </Td> </Tr> <Tr> <Th_colspan="2"> Middle school </Th> </Tr> <Tr> <Td> 11--12 </Td> <Td> Sixth grade </Td> </Tr> <Tr> <Td> 12--13 </Td> <Td> Seventh grade </Td> </Tr> <Tr> <Td> 13--14 </Td> <Td> Eighth grade </Td> </Tr> <Tr> <Th_colspan="2"> High school </Th> </Tr> <Tr> <Td> 14--15 </Td> <Td> Ninth grade (freshman) </Td> </Tr> <Tr> <Td> 15--16 </Td> <Td> Tenth grade (sophomore) </Td> </Tr> <Tr> <Td> 16--17 </Td> <Td> Eleventh grade (junior) </Td> </Tr> <Tr> <Td> 17--18 </Td> <Td> Twelfth grade (senior) </Td> </Tr> </Table>

What are the four stages of high school