What did Aristotle mean by the 'Final Cause'?

To understand Aristotle's idea of the 'final cause', you must first understand his theology on the 4 causes, as a whole. 

A brief introduction to Aristotle and his basic concepts might be a good way to start an essay. He was 17 when he moved to Athens in order to study at Plato's 'Academia'. Although the two philosophers do share some basic understandings, their focus is slightly different when it comes to asking questions about the world in which they lived. While Plato was more interested in the World of the Forms and how the contribute to our lives, Aristotle was more interested in why things exist and the reason that a certain thing exists in the space in which it does. He concluded his thinking in a discussion of the 4 causes that can reate to all things. 

The material cause- What a thing is made of- Refers to the matter/substance that something is made from- The matter of a book is paper 

Formal Cause -What makes something recognisable- What gives it its ‘form’ or ‘structure’- A book is pieces of paper arranged in a certain way 

The Efficient Cause -The agent/cause of something coming into existence- The answer to why something exists- The author of the book is the cause of its existence 

The Final Cause -The ultimate reason as to why a thing exists- Concerned with the function of anything/object- It is teleological-the reason something happens- telos refers to the final goal/purpose of something- Aristotle isn’t saying there is a purpose/design element in nature, but simply that everything has some function which is its ultimate reason- A book is the way it is so it can be read  

A statue: 

Material cause= It is made of marble 

Formal Cause= It has the shape of a statue 

Efficient Cause= A mason made it 

Final Cause= Its function is to be a beautiful statue that honours, remembers, recalls someone/thing

So, there describes the final cause. However, to get top marks you should delve a little deeper and discuss some limitations of the idea, or some positives for it. Here are a few of mine: 

-Many dispute there is a purpose in the universe 

-They say that everything can be explained by chance interaction in the universe of Scientific laws 

- However, this doesn’t explain why the laws even exist in the first place?