It is organised on the basis of four key stages, as shown here.
Schools have some discretion over when to start teaching the key stage programmes of study.
The law requires that they should be taught during the key stage, not that they be introduced at a particular time. Note about physical education The Government believes that two hours of physical activity a week, including the National Curriculum for physical education and extra-curricular activities, should be an aspiration for all schools. This applies throughout all key stages.