I teach physics. It is unquestionably the best subject. It ranges from the scale of the Universe and colliding galaxies all the way down to subatomic particles. It is the central science that underpins all the others.
It is also an amazing door-opening subject. Leading not only to physics and astronomy but all the engineerings, material science, earth science and geophysics, environmental science and climate, meteorology, optometry, medical imaging. Plus after degree all the finance, accountancy, management consulting etc....
I teach 13-18 when we can really start on the big questions and concepts.
So, why is your subject/ age the best?