 Let's see the review for lesson two. In lesson two we talked about energy intensity. You need to know what energy intensity is and you need to also know about this quadrillion BTUs. Quadrillion BTUs is 10 raised to 15 BTUs. Trillion is 12 and quadrillion is 15, 10 raised to 15. And the highlights of world energy consumption and United States energy consumption are given here. You need to know about that. There was a mistake on screen 14 of the lessons where when you put in what is the percentage of fossil fuels you put in 85% and it says wrong but that is 85% so just be aware of that. And you should also know in how to calculate doubling time. There was an equation that I'm going to provide you but that equation is 70 over rate of increase is gives you the doubling time. So there will be some numerical problems relating to this and basically it comes from the equation n equal to n0 e raised to RT. Okay so you need to know how to use this equation and calculate or project the energy demand in future and try to remember the differences between energy reserves and resources and how long each of these reserves last. Approximate numbers like you don't need to remember exact numbers but roughly what is the lifetime for coal oil and natural gas for both the United States and the world you don't have to remember about any other country. Pretty much those are the facts that you need to know for this chapter. I don't expect you to remember exact numbers statistics but you need to know the top ones like most of the petroleum is used for transportation. Most of the coal is used to generate electricity. You don't need to remember how much but you know the majority or majority of or most of the oil is used for transportation. And those kinds of you know details like you know which country has most of oil deposits or how do we do in terms of deposits etc. Those are the basic things and again you don't need to remember any of the formulas or any of the conversion factors I will provide you with those things. If you have any questions you can always you know send me a question or post a question on the message board and I'll try to answer those.