Make a Rheostat

http://www.energyquest.ca.gov/projects/rheostat.html

Make a Telegraph

http://www.yesmag.bc.ca/projects/telegraph.html

The basic form and chemistry of a battery is easy to see from building one yourself from a lemon, a strip of zinc, and another strip of copper.

Lemon Powered battery experiments

http://members.aol.com/dswart/LED.html

How to Build a Power Pack

http://www.energizer.com/learning/science/experiment.asp?ExperID=875

Make a circuit

http://www.energizer.com/learning/science/experiment.asp?ExperID=876

Human Battery Experiment

http://www.all-science-fair-projects.com/science_fair_projects/29/350/3f7eba0c64799f37d56fe612e0dd0a55.html

Make Your Own Battery - Rough Science - Island Power Plant

http://www.pbs.org/weta/roughscience/discover/powerplant.html

Potato Battery

http://www.fofweb.com/Onfiles/SEOF/Science_Experiments/5-40.pdf

http://pbskids.org/zoom/activities/phenom/potatobattery.html

Beakman's Electric Motor

http://fly.hiwaay.net/~palmer/motor.html