<Li> The IEO is conducted is a single level exam each year, but in 2017 - 2018 it was conducted on two levels . Students from class I - XII can participate in this olympiad </Li> <P> National Science Olympiad (NSO) </P> <Ul> <Li> The NSO is conducted on two levels each year . It was the first Olympiad to be conducted by SOF.It has been conducted since 1996 . Students from class I - XII may participate in the examination . </Li> </Ul> <Li> The NSO is conducted on two levels each year . It was the first Olympiad to be conducted by SOF.It has been conducted since 1996 . Students from class I - XII may participate in the examination . </Li>

How many levels are there in science olympiad