A contraction is a word made by joining two words.
An apostrophe (') shows where a letter or letters are left out.
We were not late arriving to school.
We weren't late arriving to school.
She was not excited to eat her salad.
She wasn't excited to eat her salad.
He has not finished his dinner yet.
He hasn't finished his dinner yet.
We have not been to the park today.
We haven't been to the park today.
I did not want to leave the playground.
I didn't want to leave the playground.
They are not sad today!
They aren't sad today!