Line Graph
http://www.mathgoodies.com/lessons/graphs/line.html
http://nces.ed.gov/nceskids/graphing/classic/line.asp
http://mste.illinois.edu/courses/ci330ms/youtsey/lineinfo.html
http://www.mathleague.com/help/data/data.htm
http://www.mcwdn.org/Graphs/LineGraph.html