I have to do a short powerpoint presentation in chemistry: general, organic and biochemistry, and I want a good topic.  Please help!?

Cannabis use as medicine

A good topic is whatever YOU find interesting! For myself, I like something practical.. something that people can use in their real lives.. for eg. why metal oxizides - people will remember this and not leave their tools out in the rain :-)  

How about how substance abuse affects your body? How do chemicals in our brains, create moods? Or understanding pheromones?

Since 'climate change' is now a hot topic, you could be a little controversial and talk about the grand solar minimum - how chemical changes in the sun are really what are effecting the weather.. 

hope this helps..