Help understanding the Friedmann equations?

Hello! I'm a senior at San Francisco State University, and I'm currently enrolled in a cosmology class. It's a GWAR class, meaning General Writing Assessment Requirement- I didn't expect much math. In fact, the first half of the class was basically an anthropology course, which is more in line with my interests. I was surprised when, come the second half of the coures, the 'paper' I was supposed to write was a long math explanation. I've taken three years worth of calculus plus a course on linear algebra and differential equations, so the math isn't what's difficult for me here. I believe my problem lies in understanding the concepts and variable in the equations. It seems there are a lot of different variables in the Friedmann equation that are a result of other equations, and some variables mean certain things about the universe, but getting any hard and fast information has been difficult. I'm coming to you all to see if you'll be able to provide to me an explanation of the use and composition of the Friedmann equation that I can understand. Here's the link to the paper I'm writing, so that you can see what I'm having questions about.



http://ift.tt/1ojeb1T



Any other help regarding what the assignment is asking would be appreciated as well, though hopefully I'll be able to work all of that out myself once I have a better understanding of this equation and its meaning. Thank you very much for your help.