Answer:
I am the greatest teacher out of them all, but alas in the end I kill my pupils.
If a man carried my burden, he would break his back. I am not rich, but leave silver in my track.
During the 1800's these turned women into hourglasses and is becoming more popular again these days
It's got twists and turns, but has no curves. Twist it to fix it, turn it to ruin it. What is it?
The eight of us move forth and back. To protect our king from the foes attack.
What is so fragile that saying its name breaks it?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?