Education is a progression

I have recently taken up teaching a few computer courses. When I plan them, I plan assuming that the student already has some prerequisite knowledge of element A (say) without which you cannot learn element B.

The problem begins when the person has enrolled to learn Course C without having any knowledge of Course A - B. You end up teaching him A - B - C or left gasping for air.

Education is a progression. You cannot jump to Dante or Shakspeare without an elementary appreciation of Poetry neither can you appreciate Plato or a novel if you have not already had patience with lesser books of humble length. The latter are a training for the former. They lead you to it. Without that training, you wither give up the truly noble because you haven't yet been training on those less noble stairways leading up to the great Hall.