Animated gif files -

Derived demand - http://www.reffonomics.com/deriveddemand.html

Determining the number of workers to hire: http://apecon.us/mrpmfc.gif

Rent: http://www.reffonomics.com/pureeconomicrent.html

Externalities (ooh, and they're about the environment, too!) :
http://apecon.us/externality2.gif
http://apecon.us/positiveexternaility.gif


Test tomorrow! Retests through next Tuesday (yes, before the national exam, but don't make that your ultimate focus - you need this stuff for the national exam, too!)