Is this right..?

Okay ive been using this forum to answer a lot of questions for me, so i figure you guys will be able to help with this one: i asked my coach how to do a stiff jab, and how to practice it. So he showed me, and told me to go home and hang a peice of paper from a string and practice it on the paper.. He didnt tell me how to know how i was doing it right on the paper. so i did it for about 45 min when i got home.
and i was wondering.. if any of you on here have done this:
When you do it right what the difference is on hitting the paper, from wrong
And if thats a legitimate way to tell me how to practice it.
im pretty sure he will show me more on thursday or tell me if its gotten better (Tuesday night now) but im just looking for some imput on this.?
;D

I think that everybody has their own way of teaching things- for example, the story goes that Goldman taught Marciano to throw an uppercut using towels draped over the back of bar stools- but I have never heard the piece of paper routine described. Wait and see what he tells you on Thursday.
There are a few things that go into a good, straight left hand (jab). You need to push off your back foot, not lean onto your front foot. There is a very slight turn of the hips, accomplished without shifting the weight on the feet, and a small turn of the shoulders. You need to drive the arm into full extension, and rotate your fist as you do so. And the timing of all this has to be perfect.

Alright, someone told me that it was a thing to work on speed, not power something about bruce lee practicing on newspaper for 1inchpunch, like im supposed to put holes in the paper.. but with it hanging from 1 string all i manage to do is bend the paper inwards on both sides, and make it start spinning, and go up far. so i have to re adjust the paper after 1-3 times hitting it

It sounds nuts to me.

But, hey. Maybe he knows something I don't.