Math Links
http://www.exploratorium.edu/ronh/weight/index.html
http://nces.ed.gov/nceskids/graphing/classic/bar_pie_data.asp?ChartType=bar
http://illuminations.nctm.org/ActivityDetail.aspx?ID=63
http://www.shodor.org/interactivate/activities/MultiBarGraph/
PythagoreanExplorer