Karate lessons as I have taught them

I write E=mc2 on the blackboard, "Does anyone recognize this?" Inevitably someone mentions Albert Einstein.  I say:
"Well, he wasn't so smart. Every junior engineer knows E=mv2  Einstein just said that  nothing can go faster than the speed of light (c)- very very fast. So Einstein's equation basically meant you could get a tremendous amount of energy from a teeny tiny amount of mass (like a single atom).
But let's look at the other equation. It says that if you double the mass, you double the energy, but if you double the velocity (of a punch or block), you quadruple the energy. Don't try to hit harder. Try to hit faster. And what gives you speed? your pulling hand. Try an exercise with holding a rope in the pulling hand.


Kicks:
When you first start karate, a kick is just a kick. When you reach black belt a kick is just a kick {I.e., a round kick feels like  a front snap that rotates at the last instant.

Blocks:
Try to make impact close to your opponent's wrist. Use a snap(rotation) at the end. You can execute blocks without your pulling hand; but with the pulling hand, blocks can break bones.
I think that the easiest block is the rising block; just because it is so intuitive. You instintively protect your face
Inside blocks need a pulling hand. Outside blocks work well with a follow up chop to the nose or neck. They also facilitate grabbing the opponents arm or gi to allow a side or back kick.

There is a down block too, but many people incorrectly use it against kicks. Instead use it against mid-level punches. Block kicks with kicks or with an "X" block. (E.g., block a front snap kick by positioning your foot as if you were kicking his shin. He does damage  to himself and you are unharmed. The exception may be for high rounhouse kicks where you can use both arms in outside blocks; then spin low to the floor to sweep his remaining /standing leg with the back of yours.