Macro economics

On the day I went to the vary hall to take a lecture of Macro economics. I heard this subject is required to all business school students and will be easier thatn the one I took last time.
When I enter the hall, seems like there were 50 or more students were sitting on their seat. As soon as I sat, the professor came in and starts the lecture right away. The lecture was about money, price and inflation. According to his lecture money is the wealth in the form of readily spendable purchasing power and without money our economy could not successfully function.
Also he talked ablut level of money demand and what is velosity of money and what determines it. Even though I understand the question I couldn't get the right answer because he was too fast. I thought if I had time to skim the text book I could understand more than half of thekecture.After 2 hours laterthe lecture was over and everybody went out but the professor was still doing something with his stuff so I asked him why in these days Canadian dollars became stronger than US dollars. He kindly answered me that it's because of rising oil prices. commodities which Canada is an exporter and US is an importer. Then Canada will have excess amount ofUS dollar since US buyers pay this for the goods with US dollars. This increases supply of US dollars and decreases demand of US dollars.
I told him thanks for aswering and came out of the hall.