"The law of conservation of energy tells us that we can't get something for nothing, but we refuse to believe it." Isaac Asimov
What does Asimov mean when he says this? Check out the links to do a bit of pre-search before class.
www.energy.gov/forstudentsandkids.htm
www.iptv.org/exploremore/energy/energy_in_depth/sections/potential.cfm
Can you describe yourself using the meaning of the terms potential energy, kinetic energy and activation energy? Try it.