Can Anyone Solve This?

So... I have to admit this is not my usual sort of blog post. Who blogs about Math? Not me. Because I hate it. But... Here I am doing exactly that. :)

So here's the deal. My math teacher gave us a puzzle pattern to solve, and we have to find the rule. It took me days to figure it out, but I finally did and now I want to see if you guys can. 

Here's the pattern:

1

11

21

1211

111221

312211

13112221

1113213211

31131211131221

Now what's the pattern rule? 

If you think you know the answer, comment below! And if you don't want to ruin it for yourself, then don't click the blog post permalink until you're sure you want to comment! :D I don't even care if you just noticed something or not! :D 

I'm so excited to see everyone's ideas lol.