Once there was a pen who likes to jump. It liked to jump and it liked to click. It would go jump jump jump and click click click, its tip clicking in and out. The pen love jumping so much that it jumped day after day after day but then one day it went to jump and it just went cl- and it's tip didn't click out.
So the pen went to its friend, a little boy, and told him "I think I might be broken! When I jump my tip won't click out."
The little boy said, "Oh no! we had better open you up to find out what's wrong."
So they did, and the little boy found out that the pen's spring was all worn out. So the boy took the spring to the spring store and went up to the lady who worked there and said "I came because my friend, the pen, has worn it's spring all out!"
The Spring Store employee nodded and said, "Yes... I know where you can get just the right kind of spring." And she went over to a shelf and pick a box off it and brought it back and said "this one should be the right size. Here let me take the worn out spring for you."
Then the boy took the new spring back to his friend the pen. After opening the pen back up, he put the new spring in and the pen could click again! It could jump back and forth and its tip worked perfectly!