Complex sentence: Key stage 5, is also the stage of education where students go through more intense and challenging courses in very specific subjects ie, mathematics and physics.this stage is the last stage of secondary education, if a member of sixth form.
Split into simpler sentences: Key stage 5 is also the stage of education where students go through more intense and challenging courses in very specific subjects like mathematics and physics. This stage is the last stage of secondary education for members of sixth form.