Theory:

Contraction of words refers to the process of shortening words or a group of words, wherein the omitted letter is often replaced by an apostrophe (').
Refer to the table below, for some examples:
 
No.
Words
Contracted forms
1
They areThey're
2
He/she isHe's / she's
3
It isIt's
4
That isThat's
5
There is There's
6
I willI'll
7
You will
You'll
8
He/she willHe'll / she'll
9
I amI'm
10
I wouldI'd
11
He/she wouldHe'd / she'd
12
Are notAren't
13
Will notWon't
14
Can notCan't
15
Do notDon't
16
Does notDoesn't
 
Cases of contraction used in the poem "Teamwork":
  1. It's — it is
  2. Doesn't — does not
  3. There's — there is
  4. You'll — you will
  5. That's  — that is